The History of Node.js
elegantcode.com
elegantcode.com
Not just tclhttpd, I mean, event programming in Tcl is central and there was a library called 'http' that exported a web server where you could bind urls to Tcl functions serving them.
I think it was quite clear that he spoke of his personal change in thinking about what a web server was.
AppJet and Jaxer were around way before, as well as JSDB, haXe/JS, jslibs, Narwhal... that should read "no one had succeeded before".
edit: random link sort of supporting what I thought I remembered http://www.findmeat.org/tutorials/javascript/x486110.htm
With no legacy libraries to worry about, he could build a system entirely around non-blocking IO.
Also, surprisingly enough, Javascript.