The Denver SQL Server Users group has had some really good presentations over the last couple of months on the new features in SQL 2008 including one from Paul Nielsen just last week shortly after he got back from "Jump Start" up in Redmond (if I remember the name of the event correctly).
A couple of caveats on all of the "new features" for SQL 2008, the triage to determine which features will be in the various editions is still in progress. Many/most of the new/very cool features like data compression, partitioned indexes, policies, etc. are only going to be in the enterprise edition. Unless you're planning on running enterprise edition a lot of the features that are in the CTP's will probably not be in SQL 2008 standard, etc.
On other minor but often overlooked issue - SQL 2008 will only be 64-bit, if you're buying new hardware shouldn't be an issue but if you're planning on using existing hardware... also, if you've got dependencies on third party drivers (e.g. oracle) best be sure that a 64-bit version is available/works
