I have been running Truphone on my Nokia E61 for few weeks.
Today Om Malik reports that it has raked up huge amount of VC money!
I must say the following good things about Truphone:-
1) installation (custom .cfg files) and the wizard to customized SIP profiles are too good
2) The call quality even on an Airtel Mobile Office (EDGE) connection was real good
* I made the Free call to USA at 3:30AM
I have tried mobile VOIP with Gizmo , Voxalot and a few others.
But Truphone was the winner on both availability and call quality.
Good luck to TruPhone founders! :)