If you are looking for DotNetNuke Reviews, I dug up a couple of things years ago, comparing DNN versus Sharepoint. The blog posts are from 2006, and while somewhat still valid, a lot of things have changed in both worlds. DotNetNuke provides a lot more features now than it did way back when. Sharepoint is still great for intranet setups. Coming in DotNetNuke 6.0 Enterprise Edition there will be some Sharepoint integration available as a feature.