Very interesting concept, in fact exactly the same model that was employed, and currently is, by open source developpers to answer technical issues encountered by their users.
There were always someone online in a chat room dedicated to the application.
Except that here, tweeter is in place of IRC, and that you monetize the help, in a form of currency that attracts favors.
In opensource, sharing and proving to others to be useful, is an acquired state of mind, the concept you present is a kind of pavlovian enticement.

You see, paying emotionally others in one way or other is a kind of trick, that prevents the most useful ones to be respected as natural leaders in the society, because if they have the capacity to help it is amply sufficient to prove their worth to others.
And if they want to get paid, let them be their choice, and generally they will prefer money whenever they estimate the situation to be the case.

I believe that this model will not attract the real helpers in the long run, because they do not have the essential freedom of being free to help in the way they want or they mean.
You will only attract young naive helpers for fame (and not real competent ones).

Hear hear, Liz.

My gut reaction is saying, why try to systematize people just helping out people? You don’t believe they’ll do it for free, just because they’re helpful? Why link friendly shared information to trade, economy, money, institution, control, regulation, isolation? Oops, defeated the purpose of Twitter, then. Let it be, man. It’s a good idea, but Godin might say, even though you can make money, cycles, favors, why do it?

For those who want to give back to those who’ve helped them out, pay it forward. Just spread the love. Don’t worry about keeping track. Groups of friends don’t keep a log of helpful suggestions they’ve given each other and say “you owe me”. The mob does that, and they’ve fallen apart due to infighting and mistrust. You’ll get people giving to get.

Peace.

I Twittered about it and help within 1 minute. I would have loved to credit those who helped.

Also, this is just the kind of thing I really like. If you or someone makes it, I will be a first customer!

Have you checked out Fluther? It is similar but not sms based.

Twitter will one day be remembered like a newspaper — a group that tried to maintain an unsustainable monopoly in the face of changing technologies.

And my prediction for “the future” (ie now) was for 1514 characters, the maximum payload of a IP packet!

[1] http://www.stoweboyd.com/message/2008/04/schedule.html
[2] http://www.readwriteweb.com/archives/twitpitch_the_elevator_pitch_hits_twitter.php