Hey folks, just wanted to post a quick update… my last post in figuring out how to get 1080p video onto the iPad so you can edit it in iMovie for the iPad has become somewhat redundant. The latest update for iOS devices (iOS 5.1, get it either in “General Settings > Software Update” or by connecting it to your syncing computer) now provides support for copying 1080p video from your iPhoto/Aperture library back to your iPad.
The techniques laid out however still have their merit, such as providing an archive resource for your videos (either to SD card or in iTunes project saves).
To now get 1080p videos onto your iPad in a format you can edit in iMovie, just put it into an album in iPhoto or Aperture (whichever one you're syncing with your iPad), include that album and it will automatically be there (as long as you DON'T have “ignore videos” flag in photos turned on).
Thank you Apple for finally fixing an obvious omission.