There are many webmasters reporting a huge increase in the number of links reported within Google Webmaster Tools, "links to this site" report.
There are reports at WebmasterWorld and Google Webmaster Help with webmasters asking why.
Here is a screen shot of this site's links, showing a screen shot from November 2010 till now:
I rarely look at my link counts, so I am glad I captured a screen shot back in November.
Did you see a massive increase in the number of links reported by Google Webmaster Tools?
Forum discussion at WebmasterWorld and Google Webmaster Help.