London to South of France this summer...

Battery will die.

GPS struggles to beat 5 hours and if you're using it you want to be able to trace the route.
It's a shame they haven't made dynamo chargers for them really.

Maps are better, they survive all the weather and are easier to lay out on bar tables and plan route changes on.

Did anyone use a mobile phone with gps maps, eg. iPhone, G1 or Nokia?
I'm going to cycle from cologne to london and I need a new mobile anyhow.

To do some planning, especially to estimate the climbs and descents, check out www.bikemap.net

cheers
joerg