While LTE is in development, loads in 3G networks are increasing and network operators are looking for ways to reduce their costs. One such move seems to be moving to a 'One Tunnel' architecture in which the user data packets bypass one of the packet core nodes, the SGSN.
Instead of tunneling the packets between the mobile device and the Internet through the base station, the RNC, the SGSN and the GGSN, this approach directly connects the RNC and the GGSN. As a consequence, fewer resources are required on the SGSN since it doesn't have to 're-package' the frames from one tunnel into another (hence the feature's name 'One Tunnel'). For details see this blog entry.
Nokia Siemens Networks now reports that network operator '3' in Austria is their first customer for the One Tunnel feature in this podcast that can be found here. I can imagine that they are quite keen to use the feature since Austria is a very competitive market and SIM cards and USB data sticks for 3G Internet access can be bought in every supermarket for next to nothing.