I had OSS on my boarding pass at YUL earlier this week, while I was connecting from EWR en route to YOW. At the bottom of the escalator in front of customs I asked an airport "info" person if OSS was up and running. She said yes, absolutely, head to the left and see a customs agent. There are indeed dedicated customs desks set up for OSS, and in behind them I could see the magical door that leads out into the airside section of the airport without an intermediary security stop. Customs agent was quite chatty and told me that they're pretty much ready to go with implementing OSS but are waiting until the summer busy-mess is over so they can do a slow roll out to check for any bugs. So...no such luck for me. He said they would start this fall with certain AC routes and slowly expand it. Nice chat and interesting info...though at that point I was sorry I hadn't just gone to the nexus terminal to breeze through!