Google have just announced an impressive new weapon in their ongoing war against spammy or 'unnatural' links. Webmasters will now be able visit the new 'disavow links' page and direct Google to ignore low quality links that may be harming their website's ranking. The usual course of action in these circumstances - and the one that Google still strongly advocates before you make use of the new disavow links page - is removing the bad links yourself manually.
The Disavow Tool exists primarily for webmasters who have already tried to remove bad links themselves, to no avail, and for those concerned about bad link building done on their behalf. The most crucial thing to keep in mind is that the disavow page should be a last resort measure. You're better off trying to clean up bad links yourself, as submitting multiple bad links to Google via the Disavow Tool can actually backfire and harm your position. You need to be very, very confident of what this tool is and how to use it before proceeding.
Google emphasises that if you're not sure how to use the Disavow Tool, or whether or not it's right for you, it's a good indication that it's not right for you (sort of a variation on 'if you remember the 60's, you weren't really there'!) The Disavow Tool is very exciting news for reputable SEO companies (ahem, Optimising) who can spend huge amounts of time trying to clean up bad links for clients who've previously used a dodgy SEO company.
It will also be a big help to those who've spent many frustrating hours trying to get rid of bad links with no joy. Just don't let your Great Uncle Baz anywhere near it!