It has been noted (my me, at least, but I'll bet others also) that the mere mention of Sarah Palin sets off reflexive responses, pro and con. They just burble out. In sports, the mention of Michael Vick has the same effect.
This now occurs in a new context of instant news and analysis. Though analysis may be a kind way to put it. As communication has gotten quicker and quicker over my lifetime, we hear moaning at every turn about how fast lies can spread, while the truth lags. That's always been the case, BTW. (Mark Twain: "A lie can go around the world while truth is putting its boots on.") It just seems shocking to us as all new speed is shocking. By the lag-time for truth has probably always been the same when calculated as a ratio.
But recently something new is emerging. People being so quick to judge has produced instant backlash. The Tucson shootings were played politically, but ended up at a net loss for the spinners. NFL players jumped all over Jay Cutler largely on appearances, and many are now backpedaling so they don't look like jerks. All very quick, and the quickness of the original tweets may be what set off the backlash tweets.
Perhaps it's not new. Perhaps backlash has always occurred as often and at proportionally the same speed but it just feels faster.