Some people are reporting the loss of the ability to import P2 Data using FCP 6.0.2 with Leopard (10.5 & 10.5.1) while others seem to be having no trouble. It may be a bug caused by specific software versions in conflict or specific hardware vs new software versions. The other day I was able to import P2 cards without a problem but I've gotten into the habit of importing them after copying them to a hard drive first.
Essentially, what I do is mount the P2 Cards via card slot or by mounting the camera and copying off the data directly to a hard drive then, later on, importing that into FCP. This seems to save a lot of time and hassles especially when this needs to be done on the fly depending on the conditions of the shoot.