i very much second this! PEG's the next level of regex, and i expect it to replace regex in some sense in the coming years for the whole field of text processing.
there are currently 2 of them in elisp as far as i know:
* http://www.emacswiki.org/cgi-bin/wiki/ParserCompiler (2008) by Mike Mattie.
* http://www.emacswiki.org/emacs/ParsingExpressionGrammars (2008) by Helmut Eller.
it'd be much better if PEG is integrated from the ground up in elisp, possibly implemented in C or from other libs for speed. I imagine functions that takes a regex can have a version with PEG.