The Windows Installer 4.5 SDK is also available as a separate download, and the documentation has been updated on MSDN as well. You might noticed that the SDK installation package has a familiar red motif.
If you participated in the betas, you might have noticed some changes to new features since Beta 1. The CustomAction table has a new column, ExtendedType – an I4 that currently supports msidbCustomActionTypePatchUninstall (0x0800). There’s also been some bug fixes over past versions including 4.0 on Vista and Server 2008.