Just saw Katy Perry's BBM Channel which she sometimes posts photos of her at special events. When I first joined BBM Channels, I didn't think she would make one considering all the other ones with the same name.
She occasionally posts things, but since BBM Channels isn't as easy as Twitter, I guess this is why I see few comments which some are positive, some negative, but Katy can't please everyone.
My favourite picture on BBM Channels: Keep Calm and Love Katy Perry.
Basically, the BBM app is out on all mobile platforms and if you look under channels, then search "Katy Perry", her profile should come up with a "checkmark" which means "verified account" for people not savvy with Twitter or Facebook considering how many people make Katy Perry fan accounts.
I think I found the one you mean, there are 3 certified ones, including the one you were looking at. They're all fan accounts, Katy doesn't own any of them.