There's obviously some inconsistency going on here in the app approval process, but the main gist from Apple has always been the same; they don't want users getting confused about whether or not they are chatting it up on Chess Wars or via SMS.
My company was told something similar by Apple reps at an iPhoneDevCamp event: make sure the chat bubbles look different so as not to be confused with our native app.
My company was told something similar by Apple reps at an iPhoneDevCamp event: make sure the chat bubbles look different so as not to be confused with our native app.