I love the extra power kramdown gives me, so I was surprised not to find any syntax for superscripts and subscripts other than the inelegant <sup> html injection. Are there any particular reasons support isn't built in?

The most natural syntax I've seen uses carets for super and tilde for sub:

October 31^st^
H~2~O

Are there any plans to add this to the kramdown spec/parser?

~ Jonathan Martin