So over the last while, I've been working on a PHP package imaginatively named Services_Openstreetmap, for interacting with the openstreetmap API. I initially needed it so I could search for certain POIs and tabulate the results; it's now also capable of adding data to the openstreetmap database - nodes and other elements can be created, updated and so on. It will even access the details of the user that is being used to modify that data, which is one difference between it and the other single purpose OSM frameworks.

He's submitted it to PEAR for official inclusion. Until then, you can download the package from github. The OpenStreetMap project is a community-driven mapping tool that allows users to provide new map information or make updates in an effort to keep things more up to date.