I've pushed version 0.1-8 of highlight to CRAN. highlight is a syntax highlighter for R that renders R source code into some markup language, the package ships html and latex renderers but is flexible enough to handle other formats. Syntax highlighting is based on information about the code gathered by a slightly modified version of the R parser, available in the separate parser package.
Since R 2.11.0, it is possible to install custom handlers to respond to http request (GET, POST, ...). highlight takes advantage of this and responds to urls with html syntax highlighted functions. So if the httpd port used by the dynamic help system is 9000 (hint: tools:::httpdPort) :