I see no possible benefit to invading Iran. I'm sure the government wants its resources or something (yay Middle-Eastern oil supplies...) but that is no excuse for the invasion of a country. At any rate, our military supplies are already stretched covering the stupid mess we made of Afghanistan and Iraq without a proper recovery plan.
I don't agree necessarily with the 'do not invade anywhere' thing... while I think that great caution and deliberation should be exercised when deciding whether to invade anywhere, there are some places that could genuinely benefit from outside help, like Zimbabwe. The main thing wrong with that country is Mugabe's government. My grandmother (and my mother, when she was a child) lived in nearby Botswana before Mugabe came to power, and apparently Zimbabwe was a lovely place that was doing well for itself (ie. best economy, education system etc. in Africa). Now its residents are suffering and dying, inflation in 2007 was at 8000%, 80% unemployment... violent opression of the advocates of opposing political parties... There's only so much food aid can do. In their case, it is the infrastructure that needs fixing so they can provide food for themselves!