Give them an API and they will come… Robert (Flemming) just announced a plugin for directly interfacing Ampache with SqueezeCenter. He’s also found and helped fix numerous bugs in the API, so an all around good guy. You can find his original announcements on the ampache forums and the slimedevices forums. The plugin itself is located at code.google.com/p/ampache/squeezecenter for those too lazy to click through to his announcements.
As previously mentioned there are numerous bugs in the Tagging aspects of the 3.5 API. As such I will hopefully be releasing 3.5.1 this weekend which will include those fixes.