If you can cope without using uPnP, I've used SSHFS and VLC Multicasting or Unicasting to achieve the same results.
I used SSHFS by doing the following:
sudo apt-get install sshfs vlc
sshfs user@server/path/to/video_store /local/directory
I then navigate to that directory with VLC and pick the files I want to watch with that.
If you don't have a reliable network link, then you might get some stuttering with this, but it does work.
If you've got a flat network, you might also want to consider using unicasting or multicasting from VLC.
Here's the link to how to stream using VLC:
Alternatively, you can set up multiple "channels" to watch using this howto: http://wiki.videolan.org/Documentation:Streaming_HowTo/VLM
If you need to use uPnP I've had good results streaming to my PS3 using the PS3 Media Server, although it isn't packaged in the Ubuntu repos, it is just a simple Java application that you tell it where all your video files are. It will perform some transcoding if you need that, and will transfer video, photos and music without any issues.