Is Eclipse constantly changing their API with various milestones or something? I know this is not your fault anymore, but it seems like every new Eclipse milestone breaks JBossIDE. Tried 1.5M3 with Eclipse3.2M2 and it seems to be broken again. Just giving you the heads up for the future.
Yes, they are changing the API marked as internal and one of the reasons is that we need to use them and thus they are starting to make it public.
Its unfortunately how life is on the edge of the eclipse technology at the moment....