Raphael over at the QJ.NET PSP Development Forums has just announced the public beta release of a Motion kit driver and SDK. This homebrew consists of a plugin built for custom firmwares that will enable the NeoFlash motion kit to recognize games and apps not otherwise designed to work with it.

Raphael's driver also comes with configuration menu which will allow users to set up the driver per game loaded. Lastly, the driver also fixes an issue where plugging in the motion kit would kill your sounds. You can now switch between the motion kit and headphones at will.

Keep in mind this plugin's only for PSPs running on firmwares lower than 3.71 - bad news for Slim owners. A 3.71-compatible version should be out by the driver's final v1.0 release.
The Software Development Kit (SDK) that comes with this release carries the source for libmotion_driver that allows you to interact with the driver and poll motion kit data. Raphael's also provided for a sample application to demonstrate its features.

We advise readers to visit Raphael's thread over at the QJ.NET PSP Development forums if they run into problems, given that the bundle doesn't carry a readme.