Pete--
I don't think those groups we passed en-route were the same climbers who spent the night. First, the group who spent the night on the mountain had parked next to us and I spoke briefly with the bearded gent (I recognized him from the news). Second, the climbers who spent the night had climbed Leutholds and the groups we passed continued up the south side. I'm guessing the conditions on Leutholds must have been pretty bad or they were moving very slowly. Either way, glad they made it back ok.