What I have been able to gather.....
SpaceNav support is going to be incorporated into the Blender code rather than as a plugin. Current Blender developers are focusing on getting Blender out of Beta and into a stable release before they start adding features.
Mike Erwin made serious headway with SpaceNav support during the 2010 Google Summer of Code event. http://www.invisible-cow.com/blender/soc/index.html
Status as of Jan.2 2011 -- http://www.mail-archive.com/bf-committe ... 04784.html
So the basic legwork is done.
It is now a matter of getting Blender to a stable release so his code can be rolled into it.

