This is one of those times. The process of leaving a job makes it feel so very final. A bunch of people made an effort to give you a good send off and just coming back seems like making a mockery of that. They gave you a good send off because they cared. You are the one who made the most effort and got burned the hardest. They'll understand. They'll be glad to have you back.
Hell, they might even feel like they dodged a bullet on this one and work extra hard to make sure you stop looking elsewhere for employment. "Remember that time we almost lost Bill to that startup? That was a close one, eh?"
This right here.
If you didn't have immigration status to worry about I'd say just go find another RoR job, the market is full of them ATM.
But in your case I'd say swallow your pride. You seem to be on good terms with your current team so yes this this will be a little bit awkward, but nothing more. Make a joke out of it and let people make jokes about it at your expense. Put it out in the open and laugh about it.
Don't apologize for the choices you've made (it was a business decision, not a personal one). Your manager and team will probably be relieved that you're staying, though you can probably forget any significant promotion in the short-term :)
If you can find some reasonable token of commitment (though I have no idea what that might be - anyone?), keep that in reserve.
Blame them (Flaky Corp) for acting unprofessional.
Go into your current manager, tell them you are in a really difficult and awkward situation. That you have had some communications very recently that have made you very uncomfortable with the new company and made you reconsider your decision.
Your Boss will understand that messed up stuff happens sometimes and will want to avoid interviewing for the position. Tell your Boss you honestly do not want to leave the company now given this situation and that you want your old job back.
Value yourself and take charge of the situation. Dont just allow an awkward ego-feeling or unprofessional behavior by Flaky Corp to own you!
Also, once you get your job, send http://t1.gstatic.com/images?q=tbn:yR0N5a0R8puacM:http://www... to the company who retracted the offer.
Make a joke of it. If you get your job back, take all the same people out to lunch. Play up the funny side. Give a "take me back" speech, "what was I thinking" etc etc.
Laugh at yourself, and the world with laugh with you. With your immigration status at stake, this is not the time to stand on some misplaced ego thing.