You can get one from BMW as a factory fitted extra or you could fit one yourself.
Touratech also do a 'fused' one for around £30 and it's wired direct to the battery.
It's one of the few things I miss on Mrs P's G650GS that her old F650GS already had fitted as standard.
I'm going to fit one to Mrs P's bike for her GPS and for charging over the winter with the Optimate aswell.
I'll probably just make the kit up myself and mount it where the old F650GS one was but i'll need to make a wee bracket......Either that or go for the perspex trimmed Touratech one and mount it up on the handlebar.
Mine has got one of the battery charger plugs (Din) on the the left had side of the engine.
But I was after one of the plugs by the clocks I can plug the BMW sat nav in.
Definately not on our bike, we have ABS, hazard lights, heated grips and sidestand only as it's an FL(factory lowered) and factory ordered bike..............!
I'm going to have another 'wee' look now though when i'm out checking the coo's but i know it's not there.....!
We put our socket in the right hand fairing near the clocks (just behind indicator), took careful positioning to avoid the air intake but works well there and no chance of knocking with knee.
You can just about see the socket in this picture.