Just spotted this over at textually: SMS will tell you where to find nearest cabbie
"Using a mix of satellite tracking and mobile technology, BeepTaxi links taxi drivers with customers so they don’t have to go through a radio operator.This reminds me a lot of Zingo - in fact, it seems pretty much exactly the same, really! So while I still think it's a really good application, it's not a totally new idea... Couple something like this with MCom's mobile payment system, and you've got a totally efficient and convenient taxi service, all thanks to your mobile! Great for both travellers and locals alike...
Clients only have to text their name and destination: the tracking system will find them and the closest cab driver will ring them back to arrange a pick-up."