Samsung recently announced the SCH-S310, a "3-dimensional Movement Recognition" mobile phone. It uses accelerometers to detect the relative motion of the device as an alternative user interface. While I have great hopes for gestural technologies, this isn't it.

Samsung is using this technology to replace the keypad. You can write the number "3" in the air, or mark an "x" to say no to a dialog box. Shaking the device twice will end your call.

This implementation introduces some probably fatal flaws.

1. Devices frequently move when the user is not using them, on rattling trains or bumpy roads or downward stairs. This introduces the need for a "keyguard" - I guess "motion guard" function, perhaps a "listen to me now" button.
2. Visual feedback becomes problematic because the device is moving with respect to the user's eyes. Thus either very large visual feedback, or some sort of audio or tactile feedback is necessary. Why is feedback so necessary? Well, can you imagine handwriting recognition without being able to see what your gesture actually typed? Apparently Samsung recognized this, and the device actually says "no" when you mark an "x" in the air.
3. A sequence of actions - such as entering a phone number or name - will have to have pauses between each gesture. While this will partially alleviate the visual feedback problem, it will be quite jerky for use. This raises concerns about carpal tunnel syndrome and other repetitive stress injuries.
4. Regardless of the capability of the technology, at least some users will use large gestures. This has the potential of interfering with other people nearby.
5. Standard application environments such as the browser, J2ME, and BREW fundamentally assume scroll-and-select (or possibly stylus) with some flavor of keyboard. Pretty much any application or web site will have to be redesigned to work well with gestural interaction.

There are good uses for the "movement recognition" aspects of this phone. Controlling MP3 playback (start, stop, skip) will be very useful - note the natural audio feedback. Gaming is an obvious play. But the primary value for standard phone functions is to show how you have the latest technology.