PhoneGap: Cross-Platform Mobile Device Development Solution

Nitobi's PhoneGap is an open source solution designed to give web developers JavaScript access to popular mobile device features, like the camera, GPS, the accelerometer, local SQLite databases and more, without having to write full applications.

Here's what the Nitobi developers have to say about PhoneGap at their website:

PhoneGap is an development environment for mobile application developers who want to write their code once and deploy it to multiple smartphones with as few headaches as possible. PhoneGaps supports or will support iPhone, Android, Blackberry, Palm's Pre, and Windows Mobile.

I found this informative video on PhoneGap that explains the advantages of using it and even talks about how some current iPhone apps have been build using PhoneGap: