One site PR2 -> PR0
Others unchanged.
Something that might be interesting:
The now-PR0 site had tons of dupe content added the last few months, no other change or backlinking was done. Serps are not moving ( yet? ) either.
I can't think of anything else than the dupe content. ( dupe = copy paste )
It was PR2 for approx 2 years, can't remember exactly maybe more.