Let me be frank with you, I dislike buzzwords. I hate buzzwords. Actually, I loathe buzzwords.
Why? Because they usually cloud what a message is really about, they are demeaning because it is assumed that the listener would not understand longer-than-slogan sentences and they are overused in a way so that they end up meaning something else than what they should.

AJAX is a buzzword. Web 2.0 is a buzzword. But both are incredibly useful in the change that is currently raging through the Internet.
With more and more people on the web and faster and faster Internet connections, users demand more and more. Websites have gone from simple HTML pages describing a company or listing "My favourite videos" and similar top-10 lists to Enterprise (another buzzword) systems, connecting the internal systems with external interfaces.

How many of you do NOT expect to see real-time inventory information when shopping for new hardware? How many of you are NOT expecting some sort of trouble ticket system on the website of a manufacturer of anything?
In Denmark, even the largest producers of milk have a community website with logins, discussions and company representatives participating in debates. Over dairy products!
And the users of these websites are not highly educated IT professionals - it is Mr. and Mrs. Jones from around the corner, who bought a PC in 2004 because they "wanted to see what this internal net stuff was all about".

They don't want slow page refreshes, resending data, timing out of their logins and clumsy interfaces.

What they want is Web 2.0