From the "which commands" link, it seems that they're using Blahtex to convert LaTeX to MathML:

http://gva.noekeon.org/blahtexml/

Neat feature. I think I might get a lot of use out of it as a "lighter-weight" way to write up documents that include math, using the nice LaTeX syntax, while still keeping the document as a whole WYSIWYG (better for graphics and makes it easier to avoid going back afterward for a fixing-up step). Plus, I can edit from both my Mac and iPhone with automatic sync. (There are existing LaTeX apps for iOS that can do that too, but this seems to be a solid option.)

Edit2: Tried it out on iOS. Two limitations: equations can't wrap across lines, and inserting a new equation requires a few taps - not super cumbersome but enough to discourage a "fluent" style of frequently going in and out of math mode within a sentence. Still useful.