I know I'll be in a minority here, but I'm thrilled--seriously. It shows that Ron and Rand (and don't think even for 1/1000th of a second that Rand endorsed Mitt Romney against his father's wishes) are aiming to make themselves long-term powerful players for liberty in the political process rather than those who just whine from the outside.
Ron's 2008 campaign was a glorious disaster (to quote from the title of a book about Barry Goldwater's run). It ignited a liberty movement in the GOP against the full weight of the party establishment. My participation in that campaign was a very proud moment for me. In 2012, the campaign had a much better delegate strategy-- even though it ultimately didn't pan out because Romney eliminated all non-RP competition before the convention.
We are in a position to be major players in the future of the Republican party, moving it in a pro-freedom direction. That won't be accomplished in one election, and it won't be accomplished by refusing to endorse the GOP's nominee for President, even if most RP supporters don't care for him. Ron Paul was never going to be President-- that wasn't why he ran. By Rand's endorsement, he is proving that he is willing to be a part of the GOP team, and it ensures that he and the RP movement will have a major place at the table in a Romney administration. Or, if Romney loses, it establishes Rand as a major player in the 2016 campaign for President. If Rand doesn't endorse Romney, neither of those things are remotely possible.
There are times to fight-- and we did that plenty of times-- and there are also times to cooperate because that is the best strategy for advancing your goals. Right now, the Freedom movement is best served by cooperating with the GOP nominee-- and spending most of our energy electing Pro-liberty candidates down the ballot. We will have plenty of times to fight in the future-- but in politics just as in foreign affairs, perpetual war for the sake of perpetual peace is a losing strategy