I'd take his comment with a pinch of salt, that is years before ajax applications were even mainstream.
gmail wasn't even released until 2004, and that was probably the first mass-market application that really unleashed the full power of ajax and made people stand up and notice.
What's your point with gmail? It wasn't the first AJAX app- Building HTML/PHP websites and using file uploads to a server allowed clients to edits web sites asynchronously. This is clearly before your time.
XMLHttpRequest wasn't around yet, but there were certainly ways of doing AJAXy things before GMail was popular with things like invisible refreshing iframes. I worked on such an app around 2001-2002.