I just upgraded in Lion, and also purchased an iPhone4s. I've enabled Photo Stream within Aperture, and it appears to work fine. Does anyone now how Aperture determines which pictures it streams to iCloud? From what I see, it only appears to stream stack picks. I normally download my photos as jpegs into Aperture, then stack the similar pictures. I then make stack picks, and finally rate the stack picks. Although in Aperture preferences, it says it would stream the last 30 days of photos to iCloud, it only streamed the stack picks, and not the rest of the photos. That's not really bad a thing though, since I'd only want to share the stack picks. It would be really nice if one could make photostream "smart" and only stream photos that met certain criteria, like number of stars, adjustments used, etc... like a smart album. Does anyone have any additional tips for using Photostream within Aperture?