There was a pretty bigh change in the 3.01 update (December 2007) where discovery was moved from Campus to Common Services so it had tighter integration with the DCR.
Joe Clark covered this earlier :
The interface identification is tied to ifType 24. However, if no loopback is present, the algorithm falls back to highest IP address of an ethernet interface (ifTypes 6 and 26), then highest IP address of a tokenring interface (ifTypes 8 and 9), then highest IP of a serial interface (ifTypes 22 and 53).
http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Network%20Infrastructure&topic=Network%20Management&topicID=.ee71a02&fromOutline=&CommCmd=MB?cmd=display_location&location=.2cc09faa
Why someone would actually base a network management process to even consider the existance of a token ring interface these days is beyond me.