Rolling Stone recently did an analysis of the likelihood of certain legendary bands re-forming. Here's an excerpt:
Band: Led Zeppelin
Date last seen: December 10, 2007 in London
Why you shouldnt hold your breath: Frontman Robert Plant said that the bands surviving members explored a reunion after their one-off tribute to Ahmet Ertegun, but ultimately decided they couldnt do it without late drummer John Bonham. We were incomplete, and weve been incomplete now for 29 years, Plant told Absolute Radio.