Yes, that’s big news. It’s a sorry state of affairs when it has to be regarded as such, but that’s life in the US Congress circa 2010.
What adult behavior did they exhibit? Why, they voted with Democrats to ratify New START, an arms control treaty with Russia which shouldn’t have been controversial at all.

That it was a struggle speaks more to the lack of statesmanship in the current version of the Republican party, whose leaders felt it was more important to try to score political points against the President by voting the treaty down than to restart nuclear verifications in Russia. “Loose nukes? Ha! I’d rather defeat the President in 2012,” said Senator Mitch McConnell.

Fortunately, enough of his caucus felt differently that the treaty was approved.