I picked up a Roku 3 a few days ago, and didn't expect any DLNA support out of the box, but after playing around a bit, the Roku Media Player app sees PMS, and shows up as "Media renderer was not recognized. Possible identifying HTTP headers: User-Agent: Roku/DVP-5.3 (045.03E04010A)" in the log. This is Roku version 5.3 build 4010. The app can read my shared folders, but seems to time out while reading the contents.
Has any one else seen this yet, or had any better luck getting it to work?