Since I've been the one advocating this line here, I suppose I'll have to defend it.
First off, allow me to separate myself from Bill "every war is a good war" Kristol, and the rest of the neocons, who are just parroting the official line from Israel. I don't know what their logic is, and I don't want to know, since it will all amount to rationalizations for what's going on anyway.
Secondly, I don't think Syria had anything to do with this either, except perhaps in the most tangential way. Their too close and too vulnerable, and Bashir, while hardly the brightest bulb in the series, ain't that stupid, I don't think.
Iran, however, well, Iran is a different case entirely. Let us review the history of Iran since Khomeini came into power:

1 - The hostage crisis: recall that they were released simultaneously with the inauguration of Reagan. This was too brilliant for words. They simultaneously made Carter look stupid and Reagan look magnificent, even before he got to look at the Oval Office.
2 - Next, they got Reagan to sell them arms, ostensibly to release some hostages in Lebanon. The ultimate purpose for Reagan was to funnel money to the contras in Nicaragua. Iran got its arms, Reagan got money to the contras. Meantime, they took more hostages in Lebanon anyway, not that Reagan gave a shit. Once again, breathtakingly brilliant.
3 - Recall that Iran needed those arms to fight Iraq. From here, Iran got lucky: the USSR fell, securing its northern border. Saddam invaded Kuwait, got his ass handed to him, and from then on was too weak to ever again be a threat to Iran. Whee! Finally, after those pesky Taliban folks took over Afghanistan, they went and took in Osama, who went and committed 9/11, which brought the US to oust them, and now their western border is no longer a problem.
4 - So now, their borders were doing fine. But, unbelievably, it got better: we invaded Iraq. Except, I don't think this was luck. We now know Chalabi was an agent for Iran. His influence on our decision to go to Iraq is public knowledge. Survey the entire ME, and the only nation that really benefits from our invasion of Iraq is, by no coincidence in my opinion, Iran.
5 - That brings us to the current war. Once again, survey the entire ME and the only nation that conceivably benefits from this war is, wotta freakin' surprise, Iran. As I said above, Syria doesn't benefit, in my opinion. We of course know that Hizbullah is allied with Iran. Via raf*'s post, we know that Hizbullah announced way back at the beginning of this year that they were going to attempt to free Lebanese prisoners in Israel, by taking some hostages of their own. We are in July, the second half of the year. Why did they wait so long? Because they saw the opportunity, I know. But I believe Iran saw that opportunity as well. Who saw it first is academic; I don't believe Hizbullah would have acted without consent from Iran. After all, Iran doubtlessly knew that this would be the year of the hostage as well. And as we know from #1 above, they know a thing or two about hostages and timing.

In summary, Iran has played the US like a violin for a quarter century by now. They're getting better every day at doing the same thing with Israel, and really, that's not hard at all if the pattern is always the same: poke 'em a little and they explode in anger. People like that are easy to exploit, and so are nations. Iran is far far smarter, and for them, manipulating Israel is probably child's play.
In this way, they keep Hizbullah relevant, because they know what Israel refuses to recognize, that regardless of how much physical damage gets done by all this bombing, they or some other organization will be right back, doing the same thing. The only real danger they faced was having Hizbullah be disarmed by the Lebanese government, which could really only have come about via popular pressure, and that threat, for whatever it was worth, is now gone.
But mainly, they get a nice little smokescreen to complete their nuclear program, which, if I were Iran, would be national defense priority number one, since Iraq taught everyone else a simple lesson: if you actually have nukes, the US will leave you alone.

Similar write up: Iran's Gambit
"....so far, it appears to be working."

if I were Iran, would be national defense priority number one, since Iraq taught everyone else a simple lesson: if you actually have nukes, the US will leave you alone.

If Iran has nukes, will they leave Lebanon and Israel alone?

Probably, I'd say. They can't nuke Israel without nuking all the Palestinians as well.

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I can't believe the Israelis are this stupid. But it seems they are. They fell for it, and as L pointed out somewhere else, if Israel had only gone for Hizbullah neighborhoods, it would be mostly fine with other nations. However, they chose to bomb all over Lebanon. That's a better smokescreen than Iran could possibly have hoped for.

Louns - are you seeing a lot of refugees coming in to Jordan?

Afraid I am immersed in work and unable to convey any useful on the ground comments.