I’m betting it’s the Pope’s influence. Several bishops have said something before, but it was isolated and sporadic. Giving some of them a shove, though, brings out enough simultaneously to make a much more forceful impression. Keep ‘em coming! ;-)
But is this more than the usual suspects? Chaput's always been a little more outspoken. I think a few bishops have been pushed to say something because, thanks to the internet, Catholic faithful have much more opportunity to voice publicly their dissatisfaction with wimpy bishops.
When the archbishop of Boston announces no priest may publicly celebrate a Catholic funeral for Ted Kennedy or knowingly administer communion to John Kerry or any other pro-abort pol, I'll believe the pope has a hand in the recent outspokenness. Until then, I'll believe it's the laity shining the light of Christ in our Church and the hierarchy are by and large nothing more than a bunch of political hacks.
One final thought. Even the bishops who say something, are they leaving wiggle room? I ask because they usually do. It's rare to see a firm unequivical statement, a la Bruskewitz and the Catholics for a Free Choice.