Back to Robert Plant
Plant and his newest band did an Austin City Limits, last year, and, for my money, it's one of the best ACL shows I've ever seen. He was in fine voice and his band was terrific. It was, I believe, part of his tour for "Dreamland", an album that reflects his roots in folk. He covered Jessie Colin Young ("Darkness, Darkness"), Tim Buckley, some old blues, and reinterpreted a couple of Zep songs.
I've had a love/hate relationship with Plant, since the heyday of Led Zepellin. I'm not a fan of the high pitched screeching school of blues singing, but Plant can do much more than that. The ACL shows his ability to be an interpretive singer and a highly entertaining and effective band leader.
Check it out, you might be pleasantly surprised. Also highly recommended is his anthology, "Sixty Six to Timbuktu".
As for Robbie Blunt, he's done some session work (Clannad, etc.), but appears to have peaked with his work with Robert Plant. That being said, not a bad legacy. That was some tasty stuff!