Paul Thurrott has published an update on Windows Vista Interim Build and Beta 2:

Build 5365 will include major changes to the User Account Protection (UAP) feature, my sources tell me. It is now linked to something called "Secure Desktop," which is what the CTRL+ALT+DEL keyboard shortcut will now trigger as well. Microsoft changed the behavior of UAP in order to bypass a potential flaw in the original implementation. It's unclear whether such a major change at this late stage will cause any further delays in Vista's schedule.

Other new features in build 5365 include major changes to Windows Backup and the Windows Recovery Environment, and a further deemphasizing of the virtual folders/saved searches functionality, which drops almost all support for keywords.

Additionally, Microsoft is preparing to finalize Windows Vista Beta 2 (currently set to be build 5372) on May 22, two days earlier than the previous schedule. Microsoft is planning to distribute Beta 2 at the Windows Hardware Engineering Conference (WinHEC), which is being held that week in Seattle.