The app is called Swift Key. Its for Android users and is one of the more innovative mobile tools I've seen this year.
It's a keyboard replacement and lets you type by tracing the letters and numbers on the keyboard. You spell a word by gliding your finger from one character to another...as fast as you can. It recognizes the gestures and uses a predictive software pattern to guess - with great accuracy - what you're trying to type. It supports 60 different languages. It even figures out where spaces should be.
Its really fun to use. The cost is 3-99. It doesn't work on the iPhone because Apple doesn't allow apps to change the on screen keyboard.