In the grand scheme of things, what is Iran really trying to get at in its recent move to capture British sailors?
Obviously, they aren't that afraid of the West, or else they wouldn't have made such an aggressive move. Iran is now closer to war than ever before, with the US navy scrambling to make ad hoc naval exercise as a show of force.
What Iran is doing, though, by capturing British soldiers on the eve of a critical UN vote, is sending a serious message to the West: we don't care about you, and we don't need you, and there probably isn't much you can do to stop us.
The fact of the matter, though, is that Iran's long-term game of antagonizing the West is self-defeating.
1. Iran has few active allies in this game. Only Syria, Hezbollah, and a number of Iraqi militias are willing to fight for Iran. Syria is, at best, an unreliable ally (as we saw it turn on Iraq in 1991), Hezbollah has been dealt a horribly bloody nose, and the Iraqi militia groups have been unable to force the US to leave as of yet.
2. Iran has no potential allies. While the number of PEOPLE that are outraged at US hegemony is high, the number of governments willing to actually fight the US order is zilch. China merely acts in its own self-interest in areas we care little about. Russia, while increasingly menacing and paranoid, is not enough to fight the West. And Chavez simply does not have the resources to wage a proxy war against the United States.
Furthermore, even if additional nations hopped on the anti-west bandwagon, there is no organization; communism had the monolith of the Soviet Union to guide its foreign policy. Iran IS the monolith of anti-US forces in the MidEast.
3. Iran is not served by an unstable Iraq, as the Iraq Study Group mentioned. While Iran fears the Middle East the United States may create, the alternative of an Iraq perpetually in war doesn't interest Iran much either. Unfortunately, that's what Iran is creating in Iraq right now.
In the short-run: There isn't any need to worry. The UK is drawing down troops, and the US "surge" is hardly enough to make invading Iran a cakewalk. An air strike, of course, is possible (and will probably be largely ineffective if it is targeting nuclear programs), but that is the extent of the West's willingness to fight at the moment.