Alongside an update to the OS X Lion Developer Preview 2, Apple also released a new version of Xcode 4.1 to developers, which reaches "Preview 3" status. The new build contains bug fixes and it's available now in the Mac Dev Center.
This release requires Mac OS X Lion Developer Preview 2 Update and includes iOS SDK 4.3. Continue to use Xcode 3.2.5 or Xcode 4 on a Snow Leopard partition if you plan to submit Mac or iOS apps to the App Store.
An interesting tidbit from the release notes: Xcode 4.1 Preview 3 has been "updated to support Mac OS X 10.7 Lion preview 3" -- which hasn't been released yet. Mac OS X Lion DP 2 was seeded on March 30th, a few minutes after Apple posted an update for the Developer Preview 1.