Jon Huntsman's campaign was running on fumes, down in the polls and out of money. So does it matter that he is dropping out and endorsing Mitt Romney? Yes.
A few points to consider:
Huntsman's departure is a significant boost to Romney because virtually every Huntsman vote comes from Romney. So even if he only got 4 or 5 percent of the vote in the South Carolina Republican primary, that could have cost Romney a victory. Now the more moderate wing of the party is united while the social conservatives remain divided.
Huntsman's campaign was the most effective, by far, at exposing Romney's record of flip flopping. They produced a series of devastatingly funny videos and websites (now taken down). They didn't have much money, however, so most of this stuff didn't make it on TV.
When I interviewed Huntsman seven days ago, he told me Romney was "completely out of touch." He has also called him unelectable and suggested to ABC's John Berman that he could not be trusted.