I'm surprised Jay Z won't be there, but then he wouldn't really fit in amongst this lot. Those from NJ and NYC who will appear, whilst not any of my faves either, should be there just because they were/are inevitably effected by this.
Now if Led Zeppelin are to appear I think it would be crazy to announce it as the scalpers would be having a field day, and the only money made off this should be for the Sandy victims.
However............Chris Martin from Coldplay?
Great news is it's going to be streaming on 27 web sites!

This has the makings of a great show.
Found this:
Headlined by an all-star lineup of Bruce Springsteen and the E Street Band, the Rolling Stones, Paul McCartney, The Who, Kanye West, Eric Clapton, Bon Jovi, Alicia Keys and Billy Joel, the 12-12-12 concert will be simulcast around the globe via television, radio broadcast and live Web streaming, and has the potential to reach 2 billion people during its four-hour-plus run.
According to the 12-12-12 concert’s website, “Starting at 7:30 p.m. EST, on December 12th, “12-12-12,” The Concert for Sandy Relief, will be broadcast live from Madison Square Garden via a global network of US and International television stations, CCM&E radio stations and leading web sites.”
The concert will be streamed live on 28 different websites, shown on 27 channels across the globe, presented in select movie theaters and digital billboards in New York’s Times Square, as well as in Paris and London.
“12-12-12 will be the largest concert event to ever hit the stage at Madison Square Garden, featuring the biggest names in music and the world’s leading entertainers,” event producers Clear Channel Entertainment, the Weinstein Company and the Madison Square Gardens Company said in a joint statement.