To me Iran is almost certainly pursuing a nuclear weapons program, rather than any peaceful use of the technology - its past obstruction to IAEA inspections to me indicates this most strongly, then theres the fact that Iran as an oil rich nation is not exactly short of cheap fuel for generationg electricity. Then theres the issue of whether any extra power generating capacity is needed in the first place, is Iranian industry expanding so rapidly? The idea of Iran pursuing a nuclear program for wholely peaceful reasons seems somewhat far fetched to me.
As for the US and Europe's 'interference' in iran's affairs over this nuclear program, well whilst I can appreciate its hypocritical of us to stop other nations possessing nuclear weapons when we have nukes ourselves, I don't think a nuclear armed Iran is in our interests - with the way missile technology can proliferate from North Korea and Pakistan, Europe could soon be within range of Iran. A hardline Islamic fundamentalist regime with nuclear weapons capable of hitting us....doesn't appeal to me much, but the problem is preventing it without starting WW3
North Korea has not been invaded since it would be WW3 or at least the worst war since WW2....Seoul is within twenty or so miles of the heavily militarised border area (surrounding the narrow strip that is the DMZ) so anything kicks off and it'll end up ruined due to artilltery and missile fire even before any conflict turned nuclear. Basically to go to war with North Korea would be at such a high price that even if North Korea was defeated militarily, there wouldn't be much left afterwards...
Iran would pose a significantly greater problem for the US military than Iraq would, it has a large and highly motivated army, a relatively modern and well equipped air force, and has lots of anti-ship missiles. Using what it has along with some unconventional ('terrorist' style) tactics and the US would have a hard job on its hands to win without massive losses - a simulated excercise last year had the Iranians 'win' after sinking two US Navy carrier battle groups

. The longer the Americans leave it though, the stronger Iran will become and the more likely it is to become a nuclear power. As it is though, the US military is overstretched with Iraq and as such fighting a war now would be very difficult.
Any scenario I can think of has potential to get very messy though, the Israelis won't want to even risk letting Iran become a nuclear power, and if they strike first (as I expect they'd do) the potential is there for the US to get drawn in
EDIT: Cuba is criticised for lack of press freedoms and full democratic participation, which is something of a given in a Communist state, but to the US's own measures of what makes a state good or bad means it fits into the latter category quite easily.