Nintendo announced today that it will launch Wii Sports Resort, a sequel to its flagship console game Wii Sports, and an improved version of its motion-sensing controller dubbed the Wii MotionPlus. Both are due to come out this summer.

First out of the gate is the Wii MotionPlus, a long-awaited accessory that attaches to the bottom of a Wii controller to make it more accurate. It will debut at $19.99 on June 8 in the U.S. Slated to drop on July 26, Wii Sports Resort (which, at $49.99, will come with one Wii MotionPlus) is the followup to the signature Wii Sports game that has been included for free in the more than 50 million Wii consoles sold to date.

The two products go hand in hand. Wii MotionPlus includes a gyroscope chip from Sunnyvale, Calif.-based InvenSense, giving the Wii a much better sense of human movement. The Wii Sports Resort game is designed to make the most of the Wii MotionPlus. For example, in a sword-fighting game with Wii Sports Resort, the gyro can sense the twisting of your wrist as you wave a sword around. You can also flick your wrist sideways to throw a frisbee, and you can turn the controls of a faux water jet ski to make it speed up or slow down.

The older Wii Remote controllers are less accurate because they try to fix position via a combination of infrared sensors and accelerometers. These micro-electromechanical semiconductor (MEMS) chips can only sense acceleration and rotation. But the gyroscope chips, which mimic the old gyroscopes used for ship and airplane navigation, can measure more degrees of motion. They can sense the change in position if you turn your wrist, while an accelerometer wouldn’t register any change at all.

Cammie Dunaway, executive vice president of marketing for Nintendo of America, calls the MotionPlus a “new evolution in game control.” But it’s not likely to stop there. We’ve written frequently about next-generation game controls with even more accurate camera-based sensors made by companies like 3DV Systems, PrimeSense, Canesta and others. Sixense has also been working on a magnet-based technology that does something similar. Here’s a past story on this topic.

As it stands now, there are still a lot of things you can’t do with the Wii Remote — like accurately toss a football to a player running on screen. Some existing Wii games let you do that, but they aren’t always that fun due to the inaccuracy.

The InvenSense IDG-600 chip will be used in every Wii MotionPlus. But while the Nintendo console applies this technology for fun, the gyroscope chips represent an important advance in motion sensing and position-tracking. Other uses for the gyroscope chips include image stabilization for cameras, as well as position-tracking assistance for global positioning system (GPS) tracking devices. If you lose your GPS signal, the navigation device can still track position by sensing the movement and direction of a car.

Gyroscope chips have been around for 15 years or so, while accelerometers have been around longer. The gyroscope models are more expensive, but now they’re selling in the millions and getting increasingly cheaper, said Joe Virginia, director of marketing at InvenSense. Nintendo considered using the chips in the original Wii controllers when it launched in 2006, but they were too costly. InvenSense in particular has tried to drive costs down with a new kind of MEMS design. Basically, it can put thousands of shock-resistent gyroscopes on a single chip wafer.

The Nintendo launch is a boon for InvenSense, which now has more than 100 employees. Its investors include Partech International, Docomo Capital, Foxconn, Skylight Ventures, Sierra Ventures and Qualcomm Ventures. The company has raised more than $38 million to date.