I rode as far as the Mt. Washington trail and did not see a closure sign.  Does this mean it's open?  It's fantastic.  The Olallie trail is my new favorite ride.  I ditched my bike partway up the Mt. Washington trail and hiked the last mile to the summit.  Just below the summit there is an incredible view of the Cedar River Watershed and Mt. Rainier.  There is a barrier at the junction with the Mt. Washington trail; probably to discourage bikes beyond that point, but the Green Trails map I have indicates that this is a MTB trail.   I've tried to ride up the Mt. Washington trail a few times but it is beyond my capability so I end up doing a hike-a-bike.