Android - is it possible to have 3G and Wifi connections at the same time?

I was wondering does anyone know if its possible to open a wifi and a 3g connection at the same time on And开发者_开发问答roid?

Is there any way to control access to both Wifi and 3g/GPRS data connections and use them at the same time?

At the moment it looks like OS will close the 3G data connection in the moment the wifi gets active.

For some applications it would be very nice to notify the OS that they only want to use the 3G network. This would reduce the number of data connection loss because of leaving and entering bad wifi connections.