Matt Cutts announces Google Disavow Tool. This is a great relief for websites who received the infamous Unnatural Links Warning. Matt did warn that this should be used with caution.
It is beta, experimental and the start of good things to come. Google will be launching a series of educational videos about the tool. Be cautious, and be 100% certain that you want to disavow the links. Once submitting the text file in Google WMT, give it a few days, 2-3 days should be sufficient before contacting Google through a consideration request.
Google’s announcement about the Link Disavow Tool here