Check out this prototype:
http://cooperativecars.blogspot.com/2012/06/connected-helmet.html
very cool. integrating the heart rate sensor into an existing and ubiquitous piece of gear makes it much easier to use and thus more accessible to people. hopefully it can be moved between helmets in the unfortunate event that a new helmet is required.
my running buddy's tracking his performance via smart phone, smart scale, and smart heart rate monitor (all frigging connected online, where he shares it). Just watching his progress makes me run more, I can't imagine what tracking my own would do. Can you say overtraining? Before being motivated by his stats, I'd have poo-pooed the techy-helmet geekiness as tainting the purity of man+bicycle. Now, sadly, I want one too 
I think it is an interesting product. As a first generation type of thing, I wonder what more it could do. Measure hydration, warn of over exertion (like it's possible to ride some of these hills without extreme exertion) which might lead to heart issues or heat stroke. Safety? Mind wanders...I'm sure smarter than me will think up bigger and better uses. Hopefully it catches on.
