Changes in WS08 Roles from Beta3 to the June CTP (IDS3)
A comprehensive list of the roles and features available in WS08 and the changes between the the Beta 3 and IDS3 (build 6001) has been compiled by Jose Barreto on his blog.
Lots of features have had slight name changes but I think the most significant change is the addition of IIS Web Server Role to WS08 Server Core.
To get a list of available roles and features on your WS08 install run the following command: ServerManagerCmd -query [-logPath <log.txt>]
Remember all the binaries for capabilities are available (but not expanded and installed) after a WS08 install. You will never need to find the source disk to add a role!