File transfer has not been implemented yet.
I have read a few other posts about people working on it, but I haven't seen the code yet.
As far as voice chat, you could do what I have done and setup a chat room with XIFF and then enable a streaming server (like red5 or fms) to manage the voice or video of the occupants of the room.
I wrote a JingleExtension to manage initiating and responding to the requests for voice chat.
I haven't included it in the source yet, because it's not a complete Jingle solution, but it does work for what I needed.
If people are interested, I will look into including it in the source and can be updated by others if they need more complete support.