"I got a mail back from Sonnet technical support. Looks like it's a bug in their installer, and the 2.2.1 drivers were somehow picking up cruft left behind by the earlier ones. (That may explain why some had problems but not everyone. Unless they've updated the installer since the original 2.2.1 release.-Mike)
I followed the instructions below, and have been testing things now for about three days. Fingers crossed, it all seems to work ok.
Regards Hugh
(Sonnet support's notes on removing 2.2.1/clearing the system driver cache follows:)
"I've had some folks completely purge our drivers from the system and then reload them and seen problems vanish. If you'd like to try that, do the following:

To purge the drivers in Mac OS X 10.6, open the System/Library/Extensions folder, locate SonnetSATA.kext and move it to the trash.
Go to the Finder and use the Go to Folder command (Shift-Command G) and type:
/private/var/db/receipts
locate these two files:

com.sonnettech.driver.SonnetSATA.bom
com.sonnettech.driver.SonnetSATA.plist

And drag them to the trash (give administrator password when asked)
Navigate to your System/Library/Caches/com.apple.kext.caches/Startup folder and delete the Extensions.mkext file you'll find there.
Empty the trash and restart your machine.
OS X will rebuild that mkext file without the presence of our driver. Now try re-loading 2.21 and see if the problems resolve themselves. If not, you can always go back to 2.18 or 2.19."

Hugh had mentioned monday he still had a copy of the 2.1.8 drivers but didn't keep a copy of 2.1.9. Hopefully as before (last fall when problems were seen w/2.2.0 drivers) Sonnet will re-post v2.1.9 again. (I checked again tonight and didn't see them on the Sonnet E4P drivers page.)
Clearing the system kext cache is an old troubleshooting tip but often is forgotten. (Including by me at times - thankfully my current PCIe eSATA card is natively supported.) Firmtek's drivers page has had notes about that for years. They also included downloads/utilities for cache clearing w/10.4 and 10.5 on that page for anyone that didn't feel comfortable with the manual method/instructions. (And of course many OS X utils can clear caches - LCC, Onyx, Cocktail, etc. although sometimes I prefer doing it myself as not every utility has been bug-free in some versions.) BTW - I had another person write tonight they've had no problems w/2.2.1 drivers.

Digital Camera Raw Compatibility Update 3.1 (6.77MB)
This update extends RAW image compatibility for Aperture 3 and iPhoto 09 for the following cameras:

• Hasselblad H3DII-50
• Leica M9 and X1
• Olympus E-P1 and E-P2
• Panasonic Lumix DMC-GF1
• Pentax K-7 and K-x
• Sony Alpha DSLR-A500, DSLR-A550, DSLR-A850

Requirements: OS X 10.5.8 or 10.6.2"

FYI - there's several Aperture 3 related Apple support/TS docs in today's listing.

Here's a reply from a reader today regarding the potential benefits of OS X Steam support:

"I know you probably weren't officially soliciting comments on this topic - (I was basically thinking out loud.-Mike) but my thought on a native OS X version of the Steam client is, it could turn out to be *huge* for Mac gaming. Steam was initially a big deal for Windows because it allowed software developers to sell their products in digital format to a wide audience, without having to go through a distributor who took a big cut of their profits, to get the items on store shelves. By bundling Steam with "Half Life", a game title they knew would have really big sales numbers in its retail incarnation, they were able to "legitimize" the whole Steam platform as an alternative gamers could use the next time they wanted to buy a game title.
(I've never bought a game via Steam store, although several titles (retail) used/required it. If I'd had a choice I'd have picked a non-steam version personally.-Mike)

For OS X, Steam could give smaller developers a lot more exposure when they release a game. (Titles like Braid or World of Goo would have done well as digital downloads on Steam, I think, if it was an option for them when they were first released.) In a way, I think it's too bad they didn't port Steam for OS X earlier, because Call of Duty 4 might have been the ideal game to bundle it with for Mac users. But rumor has it, Postal 3 may be coming out simultaneously for Windows, Mac and Linux, and Steam could debut with that one.
- Tom"

Good points. (And speaking of gaming, I'm also hoping for some new graphics card options this year, perhaps when the new Mac Pros are announced... that's another area where the Mac offerings are very very slim for years now. But I know you're all tired of hearing that too.)
The only reason I boot to windows is for gaming (tons of titles, many now at bargain bin prices) - but for everything else (i.e. the other 98% of the time) I use Mac OS. And I don't plan to change that regardless of what happens. (As someone already pregnant with Steam in Windows, it would take some exclusive title that I really wanted before I'd install Steam in OS X. I prefer to keep that sort of thing in the windows sandbox so to speak. But that's just my feelings on the subject.) And for the record, I've bought a lot of Mac games over the years (including COD4 for Mac even though I already had the non-steam PC version). And if the same game I wanted was available for both platforms, I'd buy the Mac version. Unfortunately often that's not been the case and with the economy like it is, I wonder what companies will make the effort (on major titles) for our small market share.

• Time for Apple to get serious about video
• iPad 1.0 is obsolete at launch
• Apple Adds and Removes 'Explicit' Category from App Store
• 6 ways iPhone and Android users differ
  
  Apps/Misc. Software Updates/Related Articles:
• Quicken for the Mac: Finally
• Quicken Essentials for Mac (product page)
• TomTom HOME 2.7.3.754
• Microsoft Keyboard 7.1 (drivers) (was IntelliType)
• Microsoft Mouse 7.1 (drivers) (was IntelliPoint)
• Backbreaker Football 1.2.1 (for iPhone/Touch)
• Rat on the Run 1.21 (for iPhone/Touch)
• Upcoming 'Vector Tanks Extreme' (for iPhone/Touch)
• Free App of the Day for Feb 25th is Graal Classic (for iPhone/Touch)

• Some pixel dimensions are slightly different after upgrade to Aperture 3
• Discussion about differences in exposure levels with Aperture 3 RAW decoding
• Aperture 3: Aperture quits when opening or when upgrade serial number is entered (revised to note 3.0.1 update fixes that)
• Aperture 3: Some metadata from XMP sidecar files may not import
• iPhone and iPod touch: Troubleshooting touchscreen response
• Accurately determine your iPod battery life
• iPod shuffle troubleshooting and service FAQ
• Updating the drivers on your Windows PC (old)

• Dell's Tablet Aims to Stick It to Apple's iPad
• Mean Time Between Failure - A Misleading Spec
• Addonics Pocket eSATA/USB 2.0 DigiDrive (w/memory card slots)
• Hands On With The Nintendo DSi XL (dual 4.2in screens)
• Nintendo DSi XL to get Classic Books App
• Hands On: The Many Layers of Metroid: Other M
• StarCraft II: Wings of Liberty (preview)
• Hands-On: Overhauled StarCraft II Welcomes Strategy Noobs
• Quake 3 On Motorola Droid
• Microsoft Takes Down Whistleblower Site, Read the Secret Doc Here
• Team Fortress 2 Update Released (yesterday)