The most recent build of 10.4.3 is said to be 8F15 and offers more bug fixes in one single update than any other in the history of system updates.
Nearly 300 fixes are addressed in the most recent build affecting almost every aspect of the Operating System, some of the items are listed; .Mac Sync, AFP, AppleScript, AppKit, Audio, Automator, Bluetooth, Calculator, Carbon Applications, DVD Playback, Dashboard, Dictionary, Disc Recording, Finder, FireWire, Fonts, Font Book, Foundation, ftp, Graphics & Video, HIToolbox, iCal, iChat, Installer, Java, Keyboard Input Methods, Keychain, Mail, Navigation Services, Networking (AirPort, Ethernet, PPP), Printing, RSS, Safari, Screen Saver, Slideshow, SMB, Software Update, Spotlight, Sync, System Preferences, USB Storage Devices, X11, and XGrid.
The release is expected to make its way public in mid to late September.