For 3 USD / day you’ll get unlimited local voice, text and 200 MB data / day. You can prepay it for arbitrary number of days.
They didn’t know the deal in the store, but found it on T-mobile website and eventually figured out, so be prepared to wait in the store. But it seems to be a real deal. I get EDGE connection in Los Angeles, no HDSPA though 🙁 However this is enough to use SSH and Maps reliably thus making life little bit easier for the country boy in this big city.
For the comparison, ATT offered 500 MB data for 25 USD, no voice, no SMS.
If you have locked phone…. well then you can just blame yourself for making a bad deal 🙂 T-Mobile does not seem to offer i-stuff.