"I have a 2010 MacBook Pro 17" with an Express Card slot, which I just updated to 10.8.2 (update went fine for me - unlike some people whom have had a very bad bad experiences). I have two USB 3 Express Cards, a Generic StarTech (Nec / Renesas Electronics based) and the Caldigit card.
Neither of them are (Natively) supported under 10.8.1 or 10.8.2.
There are no drivers found for the StarTech USB 3 card.
The CalDigit does have drivers that worked under Lion and appear to work now under Mountain Lion (at least the driver is identified under ML). However "work" is relative. Caldigit's drivers only support "Mass Storage" class device like hard drives, flash drives and some Compact Card readers for USB 2 and USB 3. If you use a device that uses a different protocol (I work with high speed FW800 / USB 2 / USB 3 cameras) like a mouse or keyboard or USB 2 to serial device, then your SOL. Repeated use of a USB 2 Camera with Caldigits' drivers will lead to a blue screen of death. (BSOD = Windows? or a KP in OS X?) You can't even do plain old Bulk transfer and I/O control without all sorts of weird errors showing up.

Secondly, when Apple announce USB 3 support for the new Macs, several developers on the Apple USB list asked if Apple supported Generic USB 3 cards. The answer was no - and that they only were supporting their own built in EXHCI controllers. They do not support generic XHCI controllers.

Lastly, Apple hasn't posted any info on their new USB 3 APIs either, so unless the device follows an Apple supported USB Class - it likely will not work at all. Developers can't add USB 3 support for them until this gets sorted out. And 3 lines in a .h header file is not documentation - that's a "Bad Apple Joke". HTH...
-Milton A."

I welcome feedback from anyone else that has tested other cards w/OS X 10.8.2 (or 10.7.5).

FYI - The Oct 3rd news page has a report from a 2008 Mac Pro owner that the Sonnet Allegro USB 3.0 PCI Express Card worked (used for AC powered mass storage/Time Machine) in OS X 10.8.2 using Sonnet driver v1.0.8. That driver version cited adding 10.8 compatibility and per their FAQ, driver 1.0.8 also supports OS X 10.7.5. (See notes on connected device compatibility on the linked product page. Oct 3rd news also had a 2nd report from an Allegro card user on issues with some bus-powered USB drives.)
There's also an Allegro USB 3.0 Express/34 card that uses the same driver so I'm assuming it should also work but welcome feedback from any owners. (Including notes on connected device compatibility/limitations.) Thanks.
  

"About iPhoto 9.4.1 (757.62 MB)
What's New in Version 9.4.1:

• Improves the reliability of syncing to iOS devices via iTunes
• Fixes an issue that could cause iPhoto to quit unexpectedly when using the Export command
• Addresses an issue that could cause iPhoto to quit unexpectedly when upgrading multiple books, cards, and calendars
• Resolves an issue with downloading and viewing photos synced from Facebook albums

System Requirements: OS X 10.7.5, OS X 10.8.2 or later"

• Troubleshooting Home Sharing
• Aperture 3.4: May quit unexpectedly on launch after updating (installer fix in 3.4.1)
• Mountain Lion: Unable to use some panes when System Prefs opened in 32-bit mode
• OS X v10.6: "You can't use this version of Mail..." alert after installing Security Update 2012-004 (if Mail app was moved)
  
  
• MacBook Pro (Retina, Mid 2012): Do not use palm rest covers (may damage display)
  
  
• iOS: AirPrint 101
• iOS: Unable to import photos to computer
• iOS: Configuring additional outgoing mail servers
• GarageBand for iOS: GarageBand may ask to access your Contacts
  
  
• iPhone and iPad: How to remove the SIM card
• iPhone: About the Cellular Data setting
• iPhone 5 (Verizon): About carrier settings update 13.1
  (fix issue where iPhone 5 may use Verizon cellular data even on Wi-Fi network)
  
  
• How to disable Cover Flow on iPod nano (4th/5th Gen)
• iPod shuffle: Using AIFF and Apple Lossless format files
  
  
• iCloud: Reminders are called Tasks in Microsoft Outlook on Windows

• Apple posts fix for Verizon iPhone 5 Wi-Fi bug
• Does the consumer hard drive have a future?
• DTS Play-Fi Wireless HD Audio Streaming Unveiled
• Krebs' Op-Ed on Browser Vulnerability
• "Looper" and The Real Science Of Time Travel
• Popular Mechanics' 2012 Breakthrough Awards
• Honda recalls more than 500K Accords (2003-2007)
• 50 Years of Space Images from European Southern Observatory
• California Bans Employers From Demanding Workers' Facebook PW