Completely lifted from http://developers.slashdot.org/comments.pl?sid=962865&cid=24989951 (it's short enough, and funny enough, and I hope the author won't mind if he finds out!)
---- quote ----
When MS uses the word Beta, they really mean pre-alpha. Release is Beta. If you want a release quality MS product you need to look for the discontinued tag.
Google is simpler, they got beta, beta and beta. One works, one doesn't, the other works for everyone except you and just when you became totally dependent on it, they kill the project.
Linux has Beta and RC. RC is solid but out of date so nvidia doesn't have drivers for it anymore, beta is solid but nvidia doesn't have drivers for it yet.
Solaris has only one version, more solid and sensible then a rock, it is labelled "Giving your accountant a heart attack".