The old edition had an SRD (I forget what that means) which was roughly the rules stripped down to basics, and no flashy pictures. 3/3.5 was open gaming, which meant any company was allowed to use it but adventures could only have the basic monsters.
4 might have its own SRD but I've read it's now only really aimed at other companies and only really now tells them what they can use. I don't know if it has basic rules for people.
Well I hunted down the SRD (seems it means system reference document) for 4th. As I thought it appears to be nothing more than a list of terms and names so developers spell stuff right
http://www.wizards.com/default.asp?x=d20/welcome
For what it's worth, this link might at least provide some information
http://www.enworld.org/index.php?page=4e
In other news, remember a few days back I said I didn't know where my dice were and I'd get a few more. Well they wanted $2 each. Gee, I told them before I paid $2 each I might just bother to look for my old ones first. It's ok they're friends of mine. Anyway it took me all of 2 minutes to find them.