Microsoft released the 1st release candidate (RC0) for SQL Server 2008 few days ago. This could means the rumoured date of a Q3 2008 released is possible.

Go here to download the bits. Note they even got a new logo for their server products (pic above)

On the mean time, I also realize that Professional Associaition For SQL Server (SQLPass.org) is offering trial SQL 2008 accounts here on top of some learning resources.