FYI, with DLNA IIRC there is only 1 mandated video and audio codec (MPEG2 and MP3 respectively), however the DMS (DLNA Media Server) and DMP (DLNA media player) may advertise support for additional codecs, via the client profile as setup via uPNP. If there are matches, the DMS and DMP may use those additional codecs. Some DLNA servers will advertise all formats/codecs as supported and will transcode on the fly to what ever the DMP wants. (MediaTomb on Linux does this).
The big problem is, a lot of appliance like devices (NASes, BR players, TVs, etc) only support the mandated codecs or they don't advertise additional supported codecs via uPNP correctly, hence a lot of people have issues. For example recent Samsung TVs do support H264 for video, but only for certain resolutions/frame rates... (The required res's and framerates are not advertised correctly, AFAIK an update will or already has fixed this), so people have a lot of issues getting it to work. Mind you LG has a similar issue, and IIRC Sony only support the mandated codecs well. (I've only got the mandated codecs to work with my Sony TV, despite having support for more than just MPEG2 when playing back from a USB key/HDD).
So, I hope that explains why Clocker is seeing 5.1 channel audio, as both his DMS and DMP support it correctly and are actually able to communicate this correctly...
PS. FYI, DLNA is based on the uPNP IP protocol, and having implemented parts of it (mainly SSDP), it's a minefield of missing details, what-if's, etc...