So what happens when you have a page with “ten PageRank points” and ten outgoing links, and five of those links are nofollowed? Let’s leave aside the decay factor to focus on the core part of the question. Originally, the five links without nofollow would have flowed two points of PageRank each (in essence, the nofollowed links didn’t count toward the denominator when dividing PageRank by the outdegree of the page). More than a year ago, Google changed how the PageRank flows so that the five links without nofollow would flow one point of PageRank each.
But this may have changed.
Andrey Lipattsev, Search Quality Senior Strategist at Google, answered a question on Google+ which may mean things have changed.
The question was:
There is a page. It links 3: 2 dofollow, 1 nofollow. What PageRank will be passed through each dofollow link: 1/3 or 1/2?
In 2009, Matt would have said 1/3rd. But Andrey Lipattsev from Google responded 1/2. He said "1/2 and you can sleep peacefully."
He did add later (translated via Russian):
Once Community against pinned, then more seriously: either 1/2 or 1/3. In the calculation takes into account many more factors than the presence or absence of certain links.
Did Google change how they handle flowing PageRank when there are nofollow links on the same page?
Forum discussion at Google+.
Update: Small update on this topic can be read here.