I've actually had exactly the opposite happen to me - I had about 30 websites all get a -50 penalty and retained their Page Rank when I sold links through a popular automated link broker. In fact my PR has stayed the same and even increased (a couple PR3 sites) - so now I consider those sites to be completely broken when it comes to Google organic serps (I'm still able to monetize them slightly, but not via traffic). This all happened 18 months ago and nothing much has changed since then.
I continue to sell links on the sites and might consider experimenting w/ some redirects since I know that I won't ever rank w/ those sites again. I tried a reconsideration request a month after it happened, but the sites are too thin and affiliate oriented for Google to put them back in their good graces. And for those of you that say, well maybe the sites got the -50 penalty for being affiliate sites, you're wrong because (in this case) the other aff sites that weren't selling links were unharmed.