indyank - 5:45 am on Nov 30, 2010 (gmt 0)
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.
It may be PR or it could be adding up to the traffic count or authority of the page linked.
I do believe that google keeps a tab on the traffic that clicks through to the no-followed link and this does help the landing page to rank better.
Hence, some value does get transferred when you are linked from a high PR page, even if it carries a no-follow tag.
For example, say, if a site is linked from wikipedia or ehow, I do see it helping the page linked.
All the above are my own thoughts/observations and google has never said that.