I was at cyclingnews.com and noticed an article on Sidi Toasters. While I don't have a pair, they sound like a great idea and the guy at cyclingnews.com loved them.
Sidi Toasters are warming insoles. OK... sticking something in your shoe to keep your feet warm is nothing new, but these are different. These insoles replace your current insole and they will keep your feet warm for 3 to 4 hours. You just need to charge them up. Also, they have a remote for turning them on and off in case your feet get to warm. They are good for hundreds of charges so if you regularly use disposable warmers in your shoes, these will eventually pay for themselves.
So... that brings us to price. These insoles cost $299 msrp. Ouch!!! That seems a little pricey for foot warmers. I would think that this should attract copy cat products depending on how good Sidi's patent is (assuming they have one).
No matter, this is a cool product that will appeal to the diehard winter riders out there. In summary, pros: keep your feet warm for a long time cons: expensive solution, but could pay for itself if you ride in cold weather a lot.