> They implemented half of Common Lisp in a markup language

Come on, S expressions are just trees, they are not God's gift to humankind.. and just because a language has an AST (surprise, a tree again!) doesn't make it a lisp. I can write a C program's AST as sexprs or a Haskell program's, yet neither will be a lisp.

S expressions are just trees. XML is just trees. But S expressions are much less verbose trees. Once you see that they're both trees, then XML looks disgustingly verbose.

XSLT is what I meant by "half of common Lisp". It's probably an exaggeration, but once you can use XML to transform XML trees into other XML trees...