gupnp-media-renderer was only meant as a proof-of-concept and hasn't been maintained for a while now. However, it has been merged into Rygel as a plugin so you want to try out rygel instead. Its available in the latest releases of all major distros so you shouldn't need to build it yourself. On ubuntu/debian, you just need to: apt-get install rygel-gst-renderer.

Someone made packages/repos for N900 as well but rygel is quite old in there.