I reported it as a bug to Apple, with specific instructions on how to reproduce the problem.
I suggest you do the same.
You can see what I found to be the specific situation in which Places is, and isn't, imported from iPhoto to Aperture in this thread:
http://discussions.apple.com/message.jspa?messageID=11229662#11229662
At least in my research, there is a workaround: Take all the Events in iPhoto which you assigned Places data at the Event level (those are the problems for Aperture Import, I've found), go into the event, select all photos in that event, and assign a Place location to them all. For whatever reason, when I assign the Place to the individual photos it gets transferred to Aperture; when I assign Place location to the Event as a whole, it does not. Buggy, but at least there is a workaround.
I am waiting for Apple to fix this bug and another one before I make the transition from iPhoto 09 to Aperture 3. In the meantime, I was just playing with A3 to see whether I like it. I do. I just don't want to lose any of the work I already did in iPhoto when I move my 17,000 photos over to Aperture.
BTW, the other thing Aperture loses when I import my iPhoto library are the Titles I've assigned to photos. A picture in iPhoto that has a meaningful Title I assigned to it gets imported into Aperture as just DSC12345xxx, losing my manual labor. Not acceptable.
...David
Message was edited by: Longwalker