It doesn't play very nicely with mobile browsers, which is a shame, so I've had to add a check against the user agent. I've also gone to town on resizing and styling parts of it to make it fit (and display) better.
Because it just replaces the textarea I don't have to do anything different to grab the contents, it just submits the form exactly as before. Pretty cool!
I may post more from the Mac just because of this.