I just started playing with a new mobile application called Fring that lets you IM and make VoIP calls to Skype and gTalk contacts. For now the software appears to be limited to a few Nokia devices. While I don’t think this is a super new project it’s the first I had heard of it. Here’s hoping 2007 ushers in a range of new mobile voice options. Get Fring here.
I think they have come a long way since you wrote the above. A few months in a start up eh.....
There's another mobile voip start up which I have started using called www.barablu.com and they also seem to be challenging Skype with a PC dialer.