You can download the Service Pack 2 CTP from the following URL:

http://www.microsoft.com/en-us/download/details.aspx?id=29848

The build # is 10.50.3720. This service pack contains all of the fixes from Service Pack 1 & Cumulative Updates 1 through 5, and a couple of other minor fixes (a couple of SSRS bugs and a bug about an ALTER TABLE batch not being cached correctly). It does not include fixes from Service Pack 1 Cumulative Update #6, which I mentioned recently.

You should *NOT* install this service pack preview if:

• your build number (SELECT @@VERSION;) is 10.00.xxxx (since this is SQL Server 2008, not SQL Server 2008 R2);
• your build number is >= 10.50.1815 and < 10.50.2500 (since you may be undoing fixes you are using from RTM CU13); or,
• your build number is >= 10.50.2811 (since you will be undoing fixes you might be using from SP1 CU6).