The idea scares the crap out of me. With a near perfect catalog now, new songs by 3 old men and 1 middle age dude under the name Led Zeppelin doesn't sound like a good idea. About new music, guitarist, Jimmy Page said he would be, "really surprised if there wasn't. We're musicians - as we're playing we'll probably be coming up with all manner of things,"
You can read about it at the BBC.
In related news their music will soon be available digitally. Changing with the times I suppose.