Trail is maintained by the Porcupine Ridge Mountain Bike Club: http://www.porcupineridge.ca/Home.html . Really, really technical single track! All rock, wood bridges, and roots - definitely a good place for fat tires, 29s, or dual suspension.
All trails are marked and rated with very nice signage, some trails are seriously technical which is a nice change from southern Ontario. Very slow but challenging ride, don't expect to blast downhill railing berms and turns here, most of the riding is slow / choosing a path over insane rocks / bridges / big climbs and steep slow descents over big rock faces. Although it sounds gnarly it is all actual maintained cut trails so there is a 'path' or line to take which is fun!
One trail has the longest wooden bridge I have ever seen, at least 200 feet of skinny bridge riding downhill!
Definitely bring a spare tube if you aren't tubeless as well.
Trail map: http://algonquinoutfitters.com/wp-content/uploads/2012/07/map_porcupine.pdf