I recently had to do a large import into a one off iPhoto library, but I didn't see an easy way to handle it in a batch. While, yes, I could just import the whole disk, I had album/folder organization that I needed to preserve.
So, after I started the first import, I went to the next folder that held photos I needed to import, selected all the photos, and dragged them to the album where I wanted them imported. When the first import was done, the next one started automatically! I then queued up the next 10 imports, and they all just worked!
The only downside I can see at the moment is that there's no sort of queue indicator, but that's a rather minor inconvenience.
[robg adds: I haven't tested this one.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090324080302294