Sign the petition if you want the remaining Beatles to stop complaining and either write some more music or go back to bathing in their cash.
Of course, it's perfectly legal for the band to continue to play live (as doing covers live has always been legal and the original artists are paid via license fees paid by the venue). They just can't put their recordings online. In fact, they could still distribute their recordings as shows as long as they called them "demos" and gave them away for free. Given they have always given their music away for free, this shouldn't be a problem.
And you can always download Beatallica using the magic of Google and bittorrent. Grab 'em while you can.
Update: Metallica are going into bat for Beatallica, contacting Sony to see what they can work out. You could argue that Metallica get the better free advertising deal from Beatallica.