Yep, have the mediaproxy module parts configured in openser.cfg, mine looks like:
 
loadmodule "mediaproxy.so"
modparam("mediaproxy","natping_interval", 30)
modparam("mediaproxy","mediaproxy_socket", "/var/run/proxydispatcher.sock")
#modparam("mediaproxy","mediaproxy_socket", "/var/run/mediaproxy.sock")
modparam("mediaproxy","sip_asymmetrics","/usr/local/etc/openser/sip-asymmetric-clients")
modparam("mediaproxy","rtp_asymmetrics","/usr/local/etc/openser/rtp-asymmetric-clients")
 
From "ps" I can see:
ps -aef | grep proxy
root     30916     1  0 14:53 ?        00:00:00 python /usr/local/mediaproxy/mediaproxy.py
root     30919     1  0 14:53 ?        00:00:00 python /usr/local/mediaproxy/proxydispatcher.py
 
 
This is from my syslog, includes info written during mediaproxy startup and a test call:
 
Feb  9 14:53:16 serbox mediaproxy[30916]: Listening for commands on local socket `/var/run/mediaproxy.sock'
Feb  9 14:53:16 serbox mediaproxy[30916]: Listening for remote commands is disabled
Feb  9 14:53:16 serbox mediaproxy[30916]: Using IP address `12.12.16.10' for the RTP/RTCP proxy
Feb  9 14:53:16 serbox proxydispatcher[30919]: Listening for commands on local socket `/var/run/proxydispatcher.sock'
Feb  9 14:53:16 serbox proxydispatcher[30919]: Listening for mediaproxy media timeout requests on 0.0.0.0:25061
Feb  9 14:53:16 serbox proxydispatcher[30919]: Default mediaproxy server is on `/var/run/mediaproxy.sock'
Feb  9 14:55:15 serbox proxydispatcher[30919]: request 71fa800f7337023a178362de41fe673b@12.12.16.9 12.12.16.9:10220:audio 12.12.16.9 12.12.16.9 remote serbox.ukgrid.net local Asterisk=20PBX info=from:0042*001@12.12.16.9,to:0044208888888@serbox.ukgrid.net,fromtag:as145fa099,totag:
Feb  9 14:55:15 serbox mediaproxy[30916]: request 71fa800f7337023a178362de41fe673b@12.12.16.9 12.12.16.9:10220:audio 12.12.16.9 12.12.16.9 remote serbox.ukgrid.net local Asterisk=20PBX info=totag:,to:0044208888888@serbox.ukgrid.net,from:0042*001@12.12.16.9,fromtag:as145fa099
Feb  9 14:55:15 serbox mediaproxy[30916]: session 71fa800f7337023a178362de41fe673b@12.12.16.9: started. listening on 12.12.16.10:60000
Feb  9 14:55:15 serbox mediaproxy[30916]: execution time:  3.73 ms
Feb  9 14:55:15 serbox proxydispatcher[30919]: forwarding to mediaproxy on /var/run/mediaproxy.sock: got: '12.12.16.10 60000'
Feb  9 14:55:15 serbox proxydispatcher[30919]: execution time:  7.59 ms
Feb  9 14:55:24 serbox proxydispatcher[30919]: delete 71fa800f7337023a178362de41fe673b@12.12.16.9 info=
Feb  9 14:55:24 serbox mediaproxy[30916]: delete 71fa800f7337023a178362de41fe673b@12.12.16.9 info=
Feb  9 14:55:24 serbox mediaproxy[30916]: session 71fa800f7337023a178362de41fe673b@12.12.16.9: 0/0/0 packets, 0/0/0 bytes (caller/called/relayed)
Feb  9 14:55:24 serbox mediaproxy[30916]: session 71fa800f7337023a178362de41fe673b@12.12.16.9: ended.
Feb  9 14:55:24 serbox mediaproxy[30916]: execution time:  0.55 ms
Feb  9 14:55:24 serbox proxydispatcher[30919]: forwarding to mediaproxy on /var/run/mediaproxy.sock: got: ''
Feb  9 14:55:24 serbox proxydispatcher[30919]: execution time:  1.59 ms