Plant has moved on from Zeppelin, but it's unfortunate. From what I've heard of his stuff with Alison Krauss (some of it's been on the DVD at work) it is an epic FAIL in comparison to something like Led Zeppelin IV.
Robert Plant has played here a couple of times and one of my friends has gone to see him he did some Zeppelin stuff but focused mainly on his own work. I don't really know if that was a good idea, but I guess artistic integrity rather > playing songs from your past.
It's a good thing that he concentrates on the present rather than the past. I've seen him live a couple of times, and yes he does 2 or 3 Zep songs, but that's it. And his stuff with Alison Krauss is not an epic failure, it has been critically acclaimed and sold out venues wherever they've played. I'd say that was a roaring success. Why should he do something that sounds like Zeppelin IV? That's probably the main reason he won't do Zeppelin, because Page is so stuck in the past.
People on here critisize McCartney for playing too many Beatles songs and not enough from his solo career. So why should it be any different for Plant? I say leave well alone, you can't recreate the past.