tedster - 9:04 pm on Jul 1, 2011 (gmt 0)
If you can actually remove all the backlnks you created (often challenging) then it's certainly worth a Reconsideration Request explaining what you did. If you can even remove most of them, still do that and try. The worst that happens is you get a note back that there is no manual penalty.
How long until the black mark is removed from your rankings is an open question. I've heard of some cases where it happened with the next spidering, and others where it seemed like a set time in the penalty box (60 days).