I don't know if it's available in the US or elsewhere yet, but I just bought an HD camera called the FunCam S-100 (or SportsCam S-100) made here in Taiwan. I too am debating on handlebar or helmet mount. After I test it out, I may start thinking of getting a second for facing the rear. I paid right at US$100 including an 8G mini SD for it. Says it'll run for 3 hours. 81x31x25.5 mm aluminum housing and 60 grams.
http://www.longintech.com/en/goods.php?id=4