Since this wasn't a big jump for Lotus and GroupWise users, I'm sure that 4.1 was an adequate tagging, assuming they wanted to keep it the same across the board. I do agree that this is a rather large jump for us Exchange users, though. I believe they've already been working on 5.0 for a few months now, but we shouldn't expect it for another year or so (from what I recall in discussions).
In the beginning the Universe was created. This has made a lot of people very angry and is widely regarded as a bad move.