This is not a question but a tip in case this happens to you. This could actually be a feature.
I shot some photos at an event today and loaded some of them into my iPad using the camera connection kit. When I got home, I placed the memory card in my reader and hit the Import button on Aperture and imported all photos (using the default where all photos are checked in the import window).
When I started to look at the project, I was amazed to see many photos missing. Why hadn't they imported? I checked the memory card in the Finder and they were all there. But why didn't they show up for import?
Any ideas yet?
OK, I'll tell you.
I have Photo Stream enabled. When I returned home, my iPad synced all the photos I had imported to the iPad to Photo Stream. Those photos then were automatically imported into Aperture via Photo Stream. Since I had “do not import duplicates” enabled in Aperture, those photos that were on the iPad didn't show up because they were already in the April 2012 Photo Stream project.
What I should have done was import all the photos to the iPad and I wouldn't have even needed to touch the camera's memory card at home. The import would be automatic as soon as my iPad connected to WiFi. Unless you depend on the import process to do a bunch of things like rename masters, this is pretty slick.
A couple of bonus thoughts:
1. I shot RAW images and the full RAW files imported to the iPad and made it intact to Aperture via Photo Stream.
2. I'm using the original iPad. Though iPhoto for iOS is not compatible with iPad 1, you can install it using Apple's iPhone Configuration Utility app. Although it seems to work fine at first, when I zoomed my RAW files, it unexpectedly quit every time. So I guess it's not a good idea after all to use it on iPad 1.
3. If you keep a referenced library, you'd need to relocate masters since Photo Stream photos come in as managed.