http://www.otmtech.com/vpen.asp
Instead, the pen converts motion at the tip into latin (or asian) characters and sends to your PDA, cell phone (think SMS), etc. It can also send the raw movements to allow you to sketch.
I've seen the idea floating around for several years, but this looks like it might be the first company to actually implement it (although their site does not mention when it will be available, so maybe not…)