This seems to be the number of titles on the Internet Movie Database right now. Not as many as I expected given that they now include individual episodes of many TV shows. I got this number by finding the highest number that works in the address field for title: http://www.imdb.com/title/tt1168191/ works, http://www.imdb.com/title/tt1168192/ (or any higher number) as of 1744 GMT on January 10th, 2008.
This reminds me of the last page on the internet.
The last person on the imdb is Darren Booth. Odd that there are less than 3 million people listed.