It won't be called 4, 3 is the last of the current trilogy. Frankly IB3 is a gorgeous mess. ChAIR loves pumping out updates, but they barely filter the bugs. Not to mention the pseudo freemium chips. The last version is usually fairly stable, but really hope the next game will be less frustrating if it ever comes.
That's implying that iPhone 4 is more powerful than the Wii U Boy, developers can't be honest with the Wii U, can they?