Well, the big thing nowadays is all the content on mobile phones and how to share it. I carry around 64GB of media (comprised of music and movies) on my N900 and having that stuck on a device with a 3.5" screen basically sucks. All the Android kids have Twonky and the iPhone does AirPlay. We've had a native DLNA client implementation for a while, servers were clunky, but, at least we don't have to spend money on more iProprietary hardware or pay for "an app" to do it.
Grab the binary package (which is optified) and install it using `dpkg -i $FILENAME` and then issue `apt-get -f install` in order to fetch the dependencies and tie them to the package. You'll need to launch it manually using `/opt/bin/fuppes` at shell prompt and you'll be up and running.
It's configurable via the web interface, you can point and click your way through configuring the bind interface as well as the ever so important media trawling directories. You can also manually edit ~/.fuppes/fuppes.cfg to your liking.
The really great feature about Fuppes isn't really described at all. It doesn't use tracker to index media. I built Fuppes with SQLite3 capabilities. It crawls and stores a separate database of media in ~/.fuppes/ and it's drop dead simple to update. Launch the server and press "u" to update it or "r" to destroy and rebuild. It'll take a few minutes to initially build, but after that - it's mere seconds to update and your media is instantly available.
I've specifically disabled transcoding since I want to keep it lightweight on mobile, taglib is giving me some problems so audio metadata and thumbnail rendering for video isn't working at the moment. I've tested it and gotten word from @Reffyyyy that it's all good for him as well. So there you have it. The power of open source compels you. Go forth and stream!