Found this article on Benchmarkreviews.com regarding how cool the new sandy bridges run. In it they claim to have a 2600K running OC'd @ 5.2 on a cheapie $26 air cooler.
http://benchmarkreviews.com/index.php?option=com_content&task=view&id=13488&Itemid=8
http://benchmarkreviews.com/index.php?option=com_content&task=view&id=13488&Itemid=8