Wii Sports Resort (and upcoming Red Steel 2 and Flingsmash) there's really only some sports games utilizing the tech. According to a recent interview with Reggie over at MTV Multiplayer, it's because Nintendo isn't really pushing for any kind of control scheme from third parties.
"What's unique with Nintendo is we don't force our developers to stick to a particular type of control scheme, and you've seen that -- everything from the new Metroid title to be single remote driven to FlingSmash utilizing the Wii MotionPlus," he said. "So it's all about what's right for the game." While we're inclined to agree with the latter part, we still wonder why nothing is using MotionPlus -- especially since it's something that greatly improves the core functionality of the Wiimote. And considering almost everyone has MotionPlus by now (or soon will, if they're Walmart shoppers looking for a great bundle), why not develop with MotionPlus in mind?
As for more MotionPlus games from Nintendo, Reggie teases "more titles that are coming" and that it "continues to be a core part of what we do." So, the take away is this: even though Nintendo just released a new piece of hardware, it's not too worried about supporting it with content -- kinda like every other peripheral the company has ever released. Yeah, we're talking about you, Wii Speak!