The NoSQL data store Riak does an interesting thing in its documentation. It features technical comparisons to seven different well-known NoSQL databases (they ought to add Redis though). Here's how they introduce their MongoDB vs. Riak comparison:
This is intended to be a brief, objective and technical comparison of Riak and MongoDB. The MongoDB version described is 2.2.x. The Riak version described is Riak 1.2.x. If you feel this comparison is unfaithful at all for whatever reason, please fix it or send an email to email@example.com.
It's pretty transparent and refreshing if you ask me. It looks like most of the comparisons are at the feature and style-of-solution level, so they haven't left much room for subjectivity to creep in. But you'll certainly want to do your own benchmarks and check out other resources. I would probably never rely 100% on this resource because I'll never trust one company to tell me the absolute truth about their solutions and other solutions, but with the community editing these docs could be the most objective you'll find on a site that's not third-party.
So, should other software products on the market do comparisons like this? Do you know of any others that do?