Business Week's Olga Kharif writes a very good summary article about Mobile VoIP, which includes client Truphone.
Olga's points about Mobile VoIP and who the players are makes a nice compendium. What this means is that Mobile VoIP has gone well beyond the blogosphere and is now going to become more mainstream.
Sadly, the carries chose not to comment. That could mean one of two things.
1) They are concerned, or starting to become concerned.
2) They have their own Mobile VoIP plans.