SQL Server 2008 Release Candidate 0 (build 10.0.1442.32) was released to MSDN and TechNet subscribers on Friday. It should be available to everyone else very soon via the Connect site.
http://msdn.microsoft.com/en-us/subscriptions/default.aspx
http://technet.microsoft.com/en-us/subscriptions/default.aspx
Apart from the new branding (see above) the goodies in this release include some Management Studio enhancements: object search, T-SQL debugger and PowerShell support. Yes, the debugger is back for those who miss it from SQL Server 2000 days!
What's also new is that multiple editions are now included in a single package, so you get Express, Standard, Enterprise, etc instead of just Developer. A product key is required to install the paid-for editions.
SQL Server Express Edition 64 bit
I have seen no info at all from Microsoft about this but RC0 does include a 64 bit version of Express Edition. This is the first native 64 bit release of Express. SQL Server 2005 Express Edition is 32 bit and WOW only.
SELECT @@VERSION;
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Microsoft SQL Server 2008 (CTP) - 10.0.1442.32 (X64)
May 29 2008 23:52:04
Copyright (c) 1988-2007 Microsoft Corporation
Express Edition with Advanced Services (64-bit) on Windows NT 5.2 <X64> (Build 3790: Service Pack 2)
(1 row(s) affected)