I'm right with EnderTheThird. Using the Wiimote would be theoretically much faster and more accurate for things like the on-screen keyboard. I've been toying around with the idea ever since I saw The Video.
On a side note, my dilema now comes down to the following. I can't install LinuxMCE on my MythTV HTPC because one, it does not integrate fully with MythTV (i.e., the plugins don't work and I want MythGame); two, it takes over the Ubuntu installation, doing all sorts of things it shouldn't do and breaking stuff like previously running apache websites, firewall scripts and network configuration, etc (i.e., you are meant to install it on a clean Ubuntu, and on its own). On the other hand, you have to use a remote with 30+ buttons on MythTV because the UI doesn't support using only a mouse, so Wiimote + MythTV is a no-go.
Meanwhile, I found this:http://www.gyration.com/en-US/ProductDetail.html?modelnum=GP2000001&accshow=3
Mouse functionality + buttons for MythTV (although not nearly enough buttons). It's not the Wiimote, but at least I'd be able to use a mouse on MythTV for web-browsing, onscreen keyboards and the occasional mouse-click on stray dialog boxes, while waiting for LinuxMCE to mature so I can move it from a virtual machine on the study to the living room TV.