tedster - 5:06 am on Nov 30, 2010 (gmt 0)
Google has never said they do that. In fact they've publicly said the exact opposite. A nofollow means no PageRank is transferred.
They do have the ability to turn off PR transfer anyway. They developed that even before the nofollow attribute was proposed.
Now if by "credit" you don't mean Page Rank in the strict sense of the term, then that is something else and very much open to speculation.