Apple has released Mac OS X 10.6.7 final version followed by a lot of builds, for all users running their machines over Snow Leopard.
The latest Mac OS X update includes hundreds of bug fixes which have been observed in previous versions of OS including Mac OS X 10.6.6 January 2011, 10.6.5 November 2010, 10.6.4 June 2010, 10.6.3 in March 2010, and 10.6.2 November 2009.
Mac OS X 10.6.7 Change Log:
Improve the reliability of Back to My Mac
Resolve an issue when transferring files to certain SMB servers
Minor Mac App Store bugs addressed
Minor FaceTime performance issues resolved
Improve graphics [...]
Apple has released Mac SO X 10.6.5 update with many fixes and enhancements. This latest Mac OS X update is recommended for all users working over Snow Leopard.
Mac SO X 10.6.5 Improvements:
Improve reliability with Microsoft Exchange servers
Address performance of some image-processing operations in iPhoto and Aperture
Address stability and performance of graphics applications and games
Resolve a delay between print jobs
Address a printing issue for some HP printers connected to an AirPort Extreme
Resolve an issue when dragging contacts from Address Book to iCal
Address an issue where dragging [...]
Apple released Mac OS X 10.6.4 update which is recommended for all users of iMac (Mid 2010). This latest Mac OS X update includes fixes from the Mac OS X 10.6.4, and also includes some new specific fixes for iMac (Mid 2010):
Resolves compatibility and performance-related graphics issues
Improves compatibility with large-format SDXC memory cards
Adds support for Magic Trackpad
Download Mac OS X v10.6.4 for iMac (2010)