Previewed at WWDC, launching in the fall.
Video Walkthrough of Mac OS X Lion Developer Seed
News of Apple's Mac OS X Lion developer seed was quickly drowned out by Apple's launch of the new MacBook Pros and this week's iPad launch news. While there's no real new news on the Mac OS X Lion front, a few more videos have been posted on YouTube providing walkthroughs of many of the features found in Apple's upcoming Mac OS X.
This particular video (embedded above) posted this past week provides a thorough walkthrough of many of the features found in Lion, if you haven't had a chance to play with it yourself.
Apple's Mac OS X Lion is expected to launch "this summer", likely near WWDC. Apple has not yet publicly scheduled WWDC for this year, but speculation has pinpointed early June as the possible date.