HappyWakeUp is a new cellphone alarm app developed for S60 (the other open platform) that only wakes you when it knows you're in a light sleep cycle. How does it know? Well, Computerworld says HappyWakeUp actually uses the microphone from your phone to statistically analyze your sleep habits based on noises you make, and when placed under your pillow, it determines what phase of sleep you're in.
HappyWakeUp runs through your normal alarm clock and won't delay the alarm any later than you have it set for. Rather, it's meant to wake you if you're in a lighter state of sleep 20-30 minutes before your wake up time, and could actually make getting up easier. [HappyWakeUp via Computerworld via Raw Feed via Wired]