I have never heard of an overall document, but the manuals for several versions are on-line at PSDN and should contain the release notes and the Getting Started manual on what's new. Given the number of different versions that people might be interested in, I don't know that it would be very practical to maintain such a document. Also, I'm not sure how relevant it would really be since there are many factors which control whether or not people keep current, but cherry picking features is probably not one of them. I.e., someone might be motivated to upgrade because of something like all the database features in 10.1B or the UI features in 10.2A, but they aren't very likely to sift through all the features to pick one version that is "good enough", as if the price varied by age.
