Can we have rel=nofollow for offsite links to deter backlink spam?

[grue]

Exactly what the title says. There was a recent case where someone was spamming backlinks to his domains, not to mention the innumerable cases of bots posting gibberish posts with many links. Adding rel=nofollow would greatly deter those spammers.

[shorena]

AFAIK is makes no longer sense for the spammers, thus it should be only a matter of time.
Backlinks from Forum spam will actually rank your website down. Not sure about the exact date, but I think they changed that earlier this year.

Adding rel=nofollow wouldnt hurt though. Might remove the posts from those users that only post links (even the spambots have more text usually)