Although I said they weren't active, they did play together in their 'nest' for a little while before settling down. In fact, it took a few camera shots before I got one that wasn't blurred.
I saw these bears on the Mappin Terraces at London Zoo in 2007, but they weren't particularly active then. Hopefully they are going to be happy at Whipsnade.
I think they are more active, they did seem to be exploring and playing together a lot more at Whipsnade, however I did see them not long after they arrived, so that might be something to do with their activity levels.