@Crell tweeted this earlier today, and it's probably worth keeping an eye on.
From the description
Geocoder is a library which helps you build geo-aware applications. It provides an abstraction layer for geocoding manipulations.
The library is splitted in two parts: HttpAdapter and Provider:
HttpAdapters are responsible to get data from remote APIs. Currently, there is one adapter for Buzz, a lightweight PHP 5.3 library for issuing HTTP requests.