Hello All! First of all I'm sorry for the crossposting.
For those who unaware of what's going inside Wireshark project - I'm working on a "classic" RTPproxy protocol dissector. Most of the patches already accepted, and Wireshark's RTPproxy parser is already usable. Few more patches should land in trunk quite soon.
As for rtpproxy-ng - I plan to add support for its protocol as well (right after I finish with this one).
If you're using Fedora Linux, then Wireshark from the repository already compiled with RTPproxy protocol dissection support.