I couldn't find his talk on the TED.com website (although I would wholeheartedly recommend checking out many of the other talks on that website). But here is another location which has several links where you can hear his talk:

http://www.cmu.edu/uls/journeys/randy-pausch/index.html

I heard that the content of his book is somewhat different and I hope to find a chance to read it in the next couple of months.