Well the rumors were true. Skype really is coming out on Tuesday (it is already tuesday in Japan and they have Skype). The folks at PC World got a sneak peak so we already know what to expect.
Only works over WiFi
Calls to landlines 2.1 cents/min
Integrated with address book
Conference calling (if someone invites you)
Chat works over the cellular network
Missing SMS, video and proper conference calling, file transfer, and voicemail