Aperture 3.4 has been released, with support for the new Shared Photo Stream that’s part of iOS 6, a menu command to open your library in iPhoto, and general “performance and stability improvements”.
I can’t update my system now as I’m at Photokina and mid-demo cycle, and upgrading now would generally be considered a Bad Idea™. I look forward to you guys downloading and letting me know how it goes!
There are many reports of crashing after upgrading, but Apple has already acknowledged the issue and posted a solution. Please read Solution to Aperture 3.4 Installation Problems.