Well if you are thinking to use nofollow for most of the outgoing links in your page, wait for few days.
Google is chaging the game on how pagerank gives important to the Nofollow.
Here are the list of few articles which might leads you guys to the world of PageRank sculpting and Nofollow.
In case you dont know what is PageRank Sculpting, here is the simple definations according to e-consultancy
“PageRank sculpting is quite simply the ‘blocking‘ of links (eg. using nofollow) to ‘sculpt‘ how much PageRank gets passed on. Using the concept of PageRank as money for an oversimplified example, let’s say you have a page with 10 PageRank dollars that it can pass on to other sites and this page includes 10 links. The idea with PageRank sculpting is that you could nofollow 5 of those links to pass on 2 PageRank dollars to each of the 5 unblocked links instead of passing on 1 PageRank dollar to all 10 of the links.“
But according to mattcutts :
“Again — and being really simplistic here — if you have $10 in authority to spend on those ten links, and you block 5 of them, the other 5 aren’t going to get $2 each. They’re still getting $1. It’s just that the other $5 you thought you were saving is now going to waste.”
So if you are getting good results after pagerank sculpting, wait for few days game might be changes to you. it takes minutes of google small change to vanish your years of effort.
Here are the list of few good articles on the topic :
1.No Clarification Forthcoming from Google on Nofollow & PageRank Flow by Rand Fiskin of SEOMOZ.
2.Google Loses “Backwards Compatibility” On Paid Link Blocking & PageRank Sculpting. By Danny sullivan from Search Engine Land
And if you are Just want to know about how Nofollow is workign good for SEO here is the article
Benifits of Nofollow as an SEO best Practice. by Patrico Robles in e-consultany.