Do we have anyone experienced enough with the US situation to make a summary of the pros and cons of different plan options in the USA?

I assume the only carrier choice for 3G is T-Mobile. I'm still undecided between a pay as you go plan with an unlocked N900 and a contract with a subsidized N900. But I have to admit that I am fuzzy on the different plans that are or might be available. Maybe I just have to wait until T-Mobile makes an announcement...