Hi with the latest upgrades available for natty narwhal, i found to my surprise that the AV Mode multimedia key now works and brings up the rhythmbox music player on press. This is the first time in 2 yrs, since installing ubuntu on this machine, that i have any of the multimedia keys working.
Mind you this is the only key which works at the moment, volume change keys, forward and backward keys and capture button for webcam do not work.
I believe this is the first step in the right direction.
Although the rhythmbox starts with the AV Button, it leaves the machines unresponsive for a minute or so. But the machine recovers on its own....Natty is still alpha1,so hopefully as it matures, will fix the issue of media keys on Vaios....