This comes as no surprise at all, except for why in the world Google waited so long to come out with a tool to disavow or block or report bad incoming links to your web site.
Yes, as we discussed in Win/Win: Block Unwanted Links In Google Webmaster Tools - Google should without a doubt create a tool for webmasters who think or know they were hit by an inorganic link penalty to tell Google these are the links and please stop counting them.
Removing these links after they are pointing to your site is a hard thing. Negative SEO is more of a concern then ever. So why shouldn't Google add this? Webmasters want it and Google could benefit from it.
The only concern, as I mentioned, it really isn't a real win/win. It is a form of mass community 'outing' without it being felt as outing anyone. It is one SEO pointing a finger indirectly at another. This is a sore topic for the SEO community.
That being said, I am surprised it took so long and as I said in the comments two weeks ago, "I really think it will happen within the next 6 months." I guess I was right because Google's Matt Cutts said so in the You&A with Matt Cutts session that "Google will work on that [a disavow link tool] in the next few months." See time stamp 4:17:23 PM and 4:48:52 PM in my live blog coverage.
I am a little sad to see so many SEOs excited for this on one hand but on the other hand, it can really help both the webmaster and Google.
Forum discussion at WebmasterWorld.