updated post: 9/16/2010: "Stub Mountain Bike Area" had soft-opening to public access in August. There will be a comment period starting before end of September to get feedback.
Original post:
Single track is done and ridable, but until signage is in place and the beginner path that threads thru middle is graded... the park ranger has these tasks on To Do... then zone remains with under construction status (ride at own risk).
On other hand, there are more than 14 miles of shared use trails in the park with much of them natural dirt surface. Much to explore if you've not been there. Gradual improvements are being made to park on a weekly basis, so trails are getting some TLC.
As part of public process for developing trails, Oregon Parks & Recreation Department has opened up a survey to capture user feedback about the Stub Stewart Trails. This has specifically been opened up to get input about Stub Mountain Bike Area trails which have been constructed by volunteer labor over the past several years. At least 90 responses are needed to meet requirements for feedback about this new trail. 
