Visual Studio 2010 Service Pack 1 is now available on MS Downloads.

You can see the full readme here, and read about it in detail on the VC Blog as well as this KB article.

The Service pack includes a number of fixes, particularly for some problems with the X64 optimizer.

Update: If you are looking for them, the locations of the Visual Studio 2010 C++ Redistributable packages for the Service Pack 1 version of the CRT can be found here.

DirectX SDK and Windows SDK 7.1 users: Be sure to see KB 2728613 and KB 2717426

Windows 8 users: Be sure to see KB 2735834 for known issues using VS 2010 on the new OS