I'm still in the process of downloading copies of the latest Panther Server and Client (I have to do so quickly, because Apple's now sending me three pestering messages a week asking me to see if they've fixed my bugs reported in 10.2).
However, there are plenty of other people on the web who are posting movies and screen shots of the latest Panther offerings.
NOTE: I am posting all of this information based on what I've found on the web, not on any personal experience with the Panther seed.
Here is a sample (with credits to MacRumors and others for finding them):
- New 3D Chess program
- New Sherlock contains a bunch more channels (since removed by Apple's request from MacMegaSite).
- Address Book synchronization with Microsoft Exchange servers (ThinkSecret)
- Mail support for Exchange mail servers (although nobody is quite certain what it does - ThinkSecret)
- Speed improvements, new application switching, ZIP compression from the finder - courtesy of AppleInsider.
All things considered, it seems to be looking good, although the number of changes at this date may bring to mind questions of when the system will ship.