^Katy is also seen to be playing the piano in an early music vid for the unreleased single "The Box".
If possible, I would love to see Katy play the piano in concert, particularly on Not Like The Movies. Or better yet playing piano and sharing vocals with Adele on Someone Like You.
However, I think she prefers playing guitar, as it is the instrument she is most familiar (and probably most comfortable) with.
IMO, the fact that Katy does play an instrument as well as write her own songs gives her a level of credibility over most other pop stars. It will be fascinating to see how her career evolves from here (post-Teenage Dream).