I have a Sony KDL40Z4100, which supports DNLA.
I found that apparently the TV only supports DNLA with respect to image files, not video or audio files. It can play back a slide show of images it detects in my UPnP directory, but it will not detect any music files on the DNS-323 at all. Apparently it can only playback audio files from a USB device plugged into its USB port. It also cannot play back videos files over DNLA.
I figure I must need to get some intermediary device, either an appliance like AppleTV or Popcorn Hour, or else build an HTPC that can stream files from the DNS-323 to the home theater receiver I have attached to the TV. If I go the HTPC route, I may end up just hosting files directly on that box, and repurpose my DNS-323 as a backup device or find some other suitable use for it.
On the plus side, the DNLA just worked flawlessly for the supported filetypes, and I had no trouble getting the TV to see the UPnP server and finding the image files or playing them as a slideshow.