the latest 'point' upgrade has now hit the Software Upgrade button on your macs, folks. You have to be running the 'crossgrade' FCP5.1 - that's the one where you sent your discs out to the tender care of the Royal Mail and hoped to see the new Universal Binary version come back to you. And if you haven't done that yet - you only have until the end of the year until they presumably whack the prices up...
Lots of new capabilities for those editing in HD in the upgrade - they also promise bug-fixes and performance enhancements, but aren't specific. All works well for me. Details on the usual Apple.com page