I've spent some time recently to look for a UPnP stack solution for android, so perhaps my exploration can be of use.
I found out that EyeconTroller is a nice media renderer. I only tested audio but EyeconTroller is supposed to handle videos as well.
I've tested it with two android devices: the first one runs iMediashare (media server), the second one runs EML UPnP-AV Controlpoint to act as a remote controller, and EyeconTroller runs on both devices. Using EML I was able to stream from iMediashare to EyeconTroller on both devices.
Next step is to stream from my linux box, but i don't expect any issue here (granted it is on the same subnet, which it is not for now), considering that EML discovered the iMediashare and all EyeconTroller instances without problem.
Note that for now EyeconTroller is free but might not always be (see eyecontec site
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