Slowtwitch just posted pics of the top 10 finishers at the recent Ironman Hawaii. The pics are quite good and talk about the shoes too. There are some shoes not very common in the regular marathon world and others popular in running aren't there. As for the marathon times, remember they swam 2.4 miles and biked 112 miles before running in stiffling Hawaiian heat. :-)
http://www.slowtwitch.com/Products/The_running_shoes_of_the_top_10_men_in_Kona_578.html
http://www.slowtwitch.com/Products/The_running_shoes_of_the_top_10_women_in_Kona_579.html