Scott, I have not run the Pikes Peak marathon yet but my friend Perry Scanlon has. He said the elevation really slows you to a fast walk. His website is www.geocities.com/cactus2clouds/skyline.html
The winner of the Mt Baldy run (4000 ft gain) did it in one hour and 9 minutes last year. It took me twice as long.
In this year's LA Marathon a 92 year old man finished the race in 4 hours and 23 minutes.