Finding a upnp streaming server for linux wasn't easy. After trying many different upnp streaming servers with DLNA support (ushare and mediatomb among others), I finally found fuppes. It supports streaming and transcoding of media files on the fly. And it works great with PS3 :)
This thread will get you started. But it is filled with xbox 360 questions and other issues:
PS3 - firmware 2.43
Ubuntu 7.10 Server (gutsy)
fuppes - svn revision 578
To make it short I did the following to get it to work:
Note that the apt-get install line has been escaped with slashes '\'. Remove them and put everything on one line if you encounter any problems.
sudo apt-get install ffmpeg build-essential libavutil-dev libavformat-dev libavcodec-dev \ subversion libtool automake autoconf libsqlite3-dev libpcre3-dev libxml2-dev \ liblame-dev pkg-config wget http://heanet.dl.sourceforge.net/sourceforge/fuppes/fuppes-SVN-578.tar.gz tar xvzf fuppes-SVN-578.tar.gz cd fuppes-SVN-578 autoreconf -vfi ./configure --enable-video-transcoding make sudo make install sudo ldconfig
Download my fuppes.cfg and put it in ~/.fuppes/fuppes.cfg
If you wish to use init.d to control your startup take a look at this howto.
UPDATE - 23. May 2009: Check out my silver bullet post about the ps3mediaserver-project