That is a brilliant idea. Not just for the reason you mentioned, but also in communicating with non-geeks.

"Oh, you're using IE from August 27, 2001? That's a little bit out of date. Because browsers update so fast, we can only support browsers released within the last 2 years." :-)

It's incredible the sound and fury generated by version numbers. Ubuntu is almost there if they would just drop the rather silly animal names and stick with 10.04, 10.10, 11.4, 11.10 et cetera. Also having such a easy to remember and unique string makes searching for support and technical questions nice.

Ubuntu's animal names make it easier to search for support and technical questions-- "maverick", "natty", and "lucid" are all much more likely to be associated with Ubuntu than numbers like 10.10.