Google is adding forum topics as deep links for some search results. These can occur for your traditional message boards or even answers sites.
Google says that the deep links will occur for sites that appear to have a large number of discussions on a given topic.
Check out this search for "laptop fan noise" and notice the forum deep links under the Yahoo! Answers result:
Meet Your Favorite Search Engine Watch Contributors
Many of SEW's leading expert contributors will be at ClickZ Live, the new online and digital marketing event kicking off in New York (March 31-April 3). Hear from the likes of: Thom Craver, Josh Braaten, Lisa Barone, Simon Heseltine, Josh McCoy, Lisa Raehsler, Greg Jarboe, Dan Cristo, Joseph Kerschbaum, John Gagnon, Eric Enge and more!