As heavily reported, the Iranians have seized three speed boats belonging to the Royal Naval party in southern Iraq after they allegedly crossed the border between Iran and Iraq. The people involved are engaged in setting up an Iraqi river police for the area (chalk up another bunch of gunmen to us! I hope I'm being too cynical), as well as attempting to catch smugglers in the Shatt al-Arab and the delta. It's the sort of thing that follows a pattern - hyperventilation all round and impressed announcements that those involved had "maps!" and "weapons!" as if that was surprising. And they are always "commandos". It was much the same when the Spanish police briefly arrested a group of supposed SAS personnel travelling by road to Gibraltar. They didn't have any weapons, it turned out - just maps and warry-looking rucksacks, but it didn't stop them from being identified on TV.
Numerous blogs are speculating that there is some link with the continuing diplomacy over Iranian nuclear ambitions, but I doubt there is any connection. This is a kind of diplomatic event that is even more ritualised than most, and if a NATO and EU partner state behaves in exactly the same way when they find someone carrying a MoD Form 90 identity card, it's only to be expected that Iran would. Iranian state TV says they will be "prosecuted" but this is likely for domestic consumption only. I predict that this will be resolved and largely forgotten within the Ali Campbell nine days' deadline.
More broadly, I don't really buy in to the idea that Iran is terrified by the occupation of Iraq. I'm sure they are intelligent enough to judge by capabilities, not by flags stuck in a map, and the US army camped in Iraq is not in a position to invade anywhere when all its efforts are absorbed in local security. The US would need enough troops to win in Iran plus an occupation force capable of covering the rear in Iraq, and at a time of serious overstretch it just doesn't happen. Add to that the fact that Iran can press the Shia button and set the south-central sector on fire at any time and I suspect they sleep well.