Even though sending the guilty guys to jail is a good thing, the growth should be put into context: Iceland is a very small economy (115-120th in the world) just comming out from a severe period of negative growth, as it can be seen here.
It is common for economies to bounce back after periods of crisis and experiment sudden explosions of high growth rates. Being such a small economy and having such a tiny population, it is very likely that Iceland just managed to overcome the crisis faster than the US.
While I'm not completely intimate to the process of bailing out banks in the US, perhaps it is still early to judge the outcome.
For example, I'm from Chile, a country which experimented a very acute crisis in the early 80's, very similar to the one currently undergoing most of the developed world (although in our case specifically contained within our economy). And the way to fix it was for the State to intervene and capitalize the banks, which literally saved the economy, jumpstarted growth and ended up with a financial sector that is currently considered the most stable and solid in the world, which among other things allowed us to pass through the current crisis completely untouched.
It took several years, however, and only in 1987-188 the economy started to see the effects of the measures. A series of very strict controls and checks were put into the bailout, in order to make sure baks would return all the money given to them (they finished paying off the whole thing in the mid-2000's). But when it was implemented, it seemed a pretty bleak scenario. It ultimately paid out, though.