Apple has just released an update to Aperture 1.5.6 (130MB):

Recommended for all licensed Aperture customers, the Aperture 1.5.6 Update addresses issues related to performance, improves overall stability, and supports compatibility with Mac OS X Leopard v10.5.

• Resolves some minor compatibility issues with iPhoto 7.1, which organizes images by Event rather than Roll.
• Addresses issues related to metadata and sort order when sharing previews with iLife Media Browser.
• Improves reliability of queries based on Import Session.
• Addresses reliability when recovering an Aperture Library from a Vault.

Update: Later today Apple will release the Aperture Export SDK 1.5.5. This provides only minor changes. Notably there are no new APIs provided. I am seeing reports that Aperture is fast on Leopard. I'll get a chance to try it out later today or tomorrow when I have Leopard in my hands.

Tags: Aperture, Leopard, Updates, iPhoto, Vaults, Plug-ins