Yes, I had thought of it and was discussing it for a client's project. However, we did not go further that route for other reasons outside of Leap and gesture interaction.
The Sketchup API for plugins seems fairly robust, so it could be that one could do a unique gesture based plugin for Sketchup. I think it would be an interesting project, maybe I will try to get something going. Busy at the moment though.
Here is somebody showing Sketchup interaction using one of the Leap mouse control apps: http://vimeo.com/81925196