The phone had been in development since 2005 under the code name "Project Purple 2" and was officially released to the public on June 29, 2007.
It was so hyped and publicized at the time that 6 out of 10 people knew about the release.
So there's your tech trivia for today.
Interestingly, the International Consumer Electronics Show was in full swing during the presentation (just as it is now), and much of the tech press left it to go cover
See Also: Here's what Apple's website looked like on the day the iPhone was announced.