Since he has now pitched in 2012, I got to poking around, and here's a few interesting little tidbits I found relating to Jamie Moyer.
Almost exactly 30 years ago, April 7 1982, Edwin Nunez made his debut for the Mariners as a 19-year old, he was the youngest player in the majors at the time. Jamie Moyer is older than Edwin Nunez.
On September 30, 1986, a 20-year-old kid named Greg Maddux made his debut, before going on to pitch over 5000 innings in a 23 year career that some people think was pretty good. Jamie Moyer had made his debut two months before this, and was already 23 years old. Some dude named Barry Bonds also began his career in 1986. A few others: Rafael Palmeiro, Mark McGwire, Will Clark.
Devon White had a 17-year career, and retired in 2001. Jamie Moyer is older than Devon White.
in 2008 a 43-year-old Kenny Rogers was the oldest player in the American League. Jamie Moyer is two years older than Kenny Rogers.
Barry Larkin and Roberto Alomar both started their careers, finished them, and were elected to the Hall of Fame within the span of Jamie Moyer's career.
By my count, 43 Major Leaguers who began their careers after Jamie Moyer have died.