A small amount of storage on your iOS device will be used. The "streaming" in iOS 6 is not what we are traditionally used to. When music is listened to the track is still downloaded to non-permanent storage. However this cache can be deleted at any time.
Now, when I am using match, I see the amount used by the music app growing and growing. Is there a limit to how much it takes up or will we have to delete at intervals to keep it from growing too large?