Ernst,
Thanks for the information. It seems that we use iPhoto for the same thing: organizing our photos. In particular we both assign places to them and both need Manage My Places because it's impossible in iPhoto to guarantee when assigning a place that its circle will not intersect that of an existing place, thereby causing that place's phots to be reassigned. Manage My Places, then, is the only way to correct the problem, and for that purpose it is barely sufficient, since the radiii of neighboring pins are not displayed along with the radius of the pin representing the currently selected place.
(Sorry, I thought I'd squeeze that in, since I asked the Apple Care agent who is trying to get an engineer to call me to have him/her read this thread first.)
But it's also evident that we have very different setups. In particular, since you're still running Snow Leopard, there are certain features of iPhoto that you cannot use.
Are you synchronizing any photos with Flickr, Facebook, etc.?
Are you surfing with a USB stick sometimes when you don't have wireless? If so, are you by any chance using Novamedia's launch2net? My answers to these two questions are: I was using a USB stick, but it is no longer supported by Lion. I suspect that drivers and kernel extensions might still be there, though. I was using launch2net, but several months ago, while I was still running Snow Leopard, it couldn't connect to my provider. I got the USB 3G modem to work with the WWAN support built into Snow Leopard, but, again, the stuff is still there.
About your feeling that the bug came with the last iPhoto update, you might be right, but the funny thing is, it doesn't seem to manifest itself in a new account as well as in a similar account on the MacBook Pro 13".
Regards,
Richard