Gaffes happen. People say stupid things that sound terrible, whether or not they're in their full context. Not all gaffes have the impact of "I voted for the $87 billion before I voted against it." The gaffes that stand out are the ones that reinforce preexisting ideas in a campaign.
Hilary Rosen's attack on Ann Romney as having "never worked a day in her life" has been the focus of the political world today. But unlike the Romney campaign's etch-a-sketch gaffe, which crystallized concerns about Romney's sincerity, the comment by Rosen does nothing to dramatize Obama's principles. Unless you want to make the argument that this attitude toward women somehow subconsciously permeates liberal thought in general, or President Obama in particular, it doesn't hold any water and isn't worth all the fuss.