I ran across yet another iPhoto "gotcha".
The only semi-approved way to migrate files with some metadata (caption, comments and date*) between iPhoto Libraries is by "sharing". It's a poor substitute for import capabilities, but this is what iPhoto's Product Management has given us. Among other limitations this kind of sharing allows one to import the last version, but not the original. The original is lost.
Tonight I tried sharing an iPhoto '08 Library from my MacBook to the main Library that sits on my iMac. (I've not yet updated to iMac to iPhoto '08 because I like to give Apple's releases two months to get the disastrous bugs out. One non-disastrous limitation is that Google's iPhoto Picasa Web Album plug-in doesn't work in iPhoto '08.) Sharing photos works, but movies aren't shared.
* I don't remember if keywords were preserved with iPhoto '07 sharing, but they aren't shared between iPhoto '07 and iPhoto '08.
So if you travel with one Library, then share your work back to the main Library on your return home, then delete the travel Library -- you lose your videos.
Lovely. Thanks again Apple!
PS. iPhoto '08 is a very good upgrade in most regards. There are lots of small fixes, overall it's a big enough improvement that even with the #$!$#!%! missing Library import it's well worth the price of iLife '08 to upgrade. I do recommend, however, using it in test mode only for at least one more month. Apple has a consistent history of disastrous iPhoto bugs with each major upgrade. Incidentally, there's something funny with the way the scroll bars work, they don't render correctly for me. I think that's because I enabled the "two arrow" hack years ago, I think I may need to undo that one.
Update 8/29: Wow, you can't even export movies from iPhoto 7.02 ('08). If you select movies then choose the "export" menu item, you get a "no item selected" message. The dialog's options make no sense for video only. It's pretty obvious Apple is trying to forget that they positioned iPhoto as a unified media library! You can click on the movie files and drag them to the desktop. When I copied them manually to my main Library they did keep the correct date attributes. I also saw my shared iPhoto 7.02 library vanish shortly after mounting in iPhoto 6. It took a while to get it back, I had to stop sharing the entire library and instead share a "smart folder" that had all photos but no movies. I was able to import all the versions (I compared counts). I confirmed that this type of "import" does discard the Originals.