Tom Dunlap of the Internet.com blog Datamation attended this morning’s keynote at the UGCX with Guy Kawasaki, a founding partner of Garage Technology Ventures and the author of eight books.

Kawasaki, who boasts 62,000 followers (including us) declared, “Twitter is the best marketing tool ever.”

And he has some advice for those who use Twitter: “Whoever follows you, you follow them…It’s an act of courtesy.”

He said there are only two kinds of people on Twitter: those who are obsessed with how many followers they have. And those who lie about not caring how many followers they have.