Slashdot and nofollow

I read that Slashdot removes the nofollow attribute of user links after a certain period of time and good karma. Does anybody know or have a clue of what are their full criteria for nofollow removal, i.e. - how many posts, age of registered account, what karma, how many achievements or other criteria.

Slashdot is very high PR site, so links with nofollow from them are very good for SEO.