One of the more interesting Jailbroken applications that appeared for the iPhone and iPod Touch has been Moo Cow Music's instrument apps which turn your iPhone or iPod Touch into a Piano, Drum, Guitar or a full Band. Youtube movie:
It appears the developer is reworking the applications for official SDK release in the future, but the most interesting discovery is that the iPhone is capable of 5-point multitouch. The video above shows 4 point multi-touch, but the developer's site indicates that up to 5 distinct points can be detected simultaneously.
From a gaming perspective, this means that complex controls can be implemented with up to 5 points of contact. While its hard to imagine a situation where 5 points of contact would come in handy (maybe the Five Point Palm Exploding Heart Technique?), it's nice to know the number of detectible presses will not be an issue.