Matt Kloskowski's Video Explaining How to Install Presets
Matt Kloskowski's Lightroom Killer Tips Blog - has regular addition of new presets
The Ultimate Free List at Pro Photography Show
Heather Green Photography - keeps a lengthy, regularly updated list of various free presets
Presets Heaven Blog - a great site that lists various free presets. Includes instruction for importing presets into LR 2.0.
A couple learning tools:
Lynda.Com has a super large library of video tutorials for Lightroom. A $25 subscription gives you unlimited access to the tutorials for one month. (I got a free one month subscription with my PS purchase. I think $25 is a bargain for the wealth of information available there!)
Scott Kelby's Lightroom book is a great reference also.