I seem to have missed this. Mixx Mobile has been updated to version 2.0. The Mixx Mobile site doesn’t tell you much about the update except for this:
With improved handling for SmartPhone we have greatly optimized the workflow for creating ringtones. Mixx Mobile 2.0 provides full support for Windows Mobile 6.1 and includes many other improvements. Try it out and see for yourself!
I’ll have to see if I can get an updated version to check it out.