The credits on barnesandnoble.com say the following people performed on the new album:
Little Richard
Jeff Lynne
Graham Nash
Ringo Starr
Joe Vitale
Kenny Passarelli
David Crosby
Jim Fox
Dale Peters
As well as others but these were the most notable.
Ranked:
1.When The Levee Breaks
2.How Many More Times
3.The Ocean
4.Bring It On Home
5.Tea For One
6.I'm Gonna Crawl
7.Sick Again
8.Hats Off To Roy Harper