Marcia - 10:02 pm on Dec 11, 2007 (gmt 0)

I've seen several sites that went PR0, and the common denominator was that they were very "stale" and it had been ages and ages since they had acquired any new IBLs (with the exception of the ever-present scrapers).

I wouldn't surmise it's a penalty, especially if it's a large site with a lot of IBLs. How long had it been since any content was updated, and how long since there were any fresh, decent quality inbound links.

I'd have to dig out which ones, but there are several papers out there that very specifically mention freshness as a factor that's taken into consideration. And another recent patent application as well, that goes into computing average age for the link profile.