Don't think so...
The difficulty in evaluating them is that they have a lot of crossover functionality (especially in regards to CMS).
There are obvious differences (platform, open vs closed source, etc.), but at the end of the day I think you're best choosing the features that one platform has that the other does not (i.e. I believe I can create an application, in the form of a portlet, and run it under Liferay that I could not do in SharePoint, but I could be wrong, but you can use sharepoint to manage shared editing of MS Office documents that is not easily handled by Liferay).
At one point there was a Sharepoint integration layer for Liferay, but I don't know if that's still active and/or available.
