Apple recently sent out OS X 10.6.8 to developers. Macrumors (via fscklog.com) said that the update will essentially prepare our Macs for OS X Lion.
The update will remove MacDefender from computers. MacDefender is a Malware that went around a few weeks back and was installed on user computers while they browsed. The unfortunate thing is that it shares a name with a legitimate dude who goes by Mac Defender (and has for years) and has absolutely nothing to do with the malware.
Also big news is that this, if the image is real, will "enhance the Mac App Store to get your Mac ready to upgrade to Mac OS X Lion." It's expected that Apple will reveal more about Lion at Worldwide Developers Conference '11 (WWDC '11).
The update is also said to have a few other features such as resolving an issue that causes Preview to quit unexpectedly and improve VPN reliability.