From Wireless Week:

Battery life has always been an issue. It is one of the more mundane, yet increasingly prominent challenges in the wireless world. Phones are becoming more powerful, applications more complex, and even though batteries are not benefactors of Moores Law, they too are getting slimmer, lighter and longer lasting. But there comes a point, and its fast approaching, that battery technology will hit a wall physically unable to get any smaller, yet under increasing pressure to have more oomph! After Trevor Baylisss famed clockwork radio, the UK has spawned yet another mighty innovator, Peter Ash a 16 year old schoolboy who hooked up his sisters hamster wheel to a phone charger, and hey presto! Free juice. Rumours that Fitness First is teaming up with Carphone Warehouse to offer a corporate solution to recharging batteries remain, at this stage, a complete fabrication.

Telecoms.com