I have just returned from interrailing around europe. I viewed the photo's in Picassa and Windows Picture viewer. I tried to import them using Picassa. My laptop ran out of charge along the line and all photo's on the memory card were deleted, and no picture transferred to my computer. I have since left the card into a photo store, but are the pictures in temp files or some where?? Get Sandisks Rescue Pro software. Photos aren't actually deleted until something is written over them. I would definitely send feedback to the google team if this is the case. The originals should never be deleted until the copies are complete. Fortunately there is software out there that can recover the pictures after they are deleted off a camera.
If you leave picassa running it will continually index your hard drive and should find them if they are out there somewhere.
I would check the picassa forums for more info http://groups.google.com/group/picasa | 