OS X 10.6.4 soon to be released
Apple Seeds New Mac OS X 10.6.4 Build 10F37 | iPhone in Canada Blog - Tips, Tricks, News, and Tutorials for Canadian iPhone Users
Today Apple seeded the first build of OS X 10.6.4, build 10F37.

According to reports, the current build focuses on Graphics Drivers, SMB, Time Machine backups, USB, and VoiceOver. The build does not include any further updates or enhancements.

There was also one Known Issue identified as:

Password will be requested when launching iChat