Rui Carmo
An interesting read, and a timely reminder that there are a lot of traditional, background (almost legacy) services that can be exploited on any mobile device.
The Visual Voicemail bits were especially interesting to me, since I was involved in getting that to work at Vodafone and I always felt the entire thing was a bit of a hack (for which our voicemail provider - Comverse at the time, if I recall correctly - happily charged us an insane amount of money, but I digress).