A quick update about SQL 2008 and how that can enhance Sharepoint 2007. The main word is compression of data in different scenarios. Backups from SQL-server can now be compressed which saves space needed for backups, which have been a big problem for us as it admins. Also the replication traffic between sql nodes in the sql cluster is compressed which makes mirroring easier and more effective if the infrastructure isn’t a high-bandwith one. I have just installed my first SQL 2008 machine in production and will be updating with more info as soon as I have something fun to tell you about it! =)
More detailed information can be found at Technet.