there has been no evidence in those nearly four years that Adsense links would count in tha algorithm in any way.
I was thinking in more simple terms and not necessarily in the algo, bear with me.
- Page has 12 internal links and no ads, each link gets 1/12 of the pagerank to pass along (assuming all are related, etc,etc)
- Page has 12 internal links and 4 ads in one unit, each INTERNAL link only gets 1/16 of the pagerank to pass along due to the four extra ads. The ad link values don't pass to the advertisers, they are simply dropped a la nofollow.
edit: I'm asking this in part because the number of links in an adsense unit fluctuates and I was wondering how much link churn impacts a page, but that's for another thread. If adsense links DO play a role and DO cause some rank to drop then there might be an optimal ratio to target, a guide as to how many ads a page can support depending on how many other links are on the page etc.