We were on Liberty Ridge the weekend of May 12th. The Carbon goes, but the route we took accessed the ridge on the west side, not the east side as shown in most of the guide books. Got as high as Thumb Rock, then awoke to windy conditions and fresh snow, so made a retreat. Like Mike said, it looked really icy above Thumb Rock, but we talked to a couple of guys who had climbed it the previous Thursday, and they said it was solid.