It's changed names
I know this is an old thread but it comes up on the first page of a google search for "maxell pen-it", so I though I'd put this information out there for others to benefit.
The "Maxell Pen-It" pen technology has been purchased (or is now used and branded) by Anoto themselves. I got an Anoto Digital Pen since I'm writing documentation for a software that will use its technology, and after looking at a picture of the Pen-It, it's obvious that it's exactly the same.
With the use of Anoto's PenDirector software, you can grab the PGC (Pen Generated Coordinates) files straight from the pen and do... Well, something with it. Not sure what software can support PGC files, and I'm certainly not going to advertise my own company on a first post on this board (especially since the cost of our software is prohibitive to any but medium to large companies).
So the gist of it: If you have a technology that uses the Anoto Digital Pen model DP-201 , your Maxell Pen-It *should* work with it also.