The Samsung Note3 (and presumably later versions) come with S Note (which I just found is also available for windows[1]) -- and does a decent job of translating hand-drawn equations (eg sum over x=0 to infinity for 1/x). Not sure about the pc version (yet). Might be worth looking at for those that have a windows tablet/device with stylus input.

[ed: Doesn't appear to be a feature of the windows/desktop app :-( ]

[1] http://www.samsung.com/uk/apps/mobile/snote/