Here's video of the final round and a link to the complete fight...

ROUND 11
Left hook by Cotto. Margarito lets fly a combination. Margarito lands a right. Good counter right-left by Cotto. Left hook by Margarito. Margarito lands a left. Cotto seems to be hurt. Right uppercut and Cotto takes a knee. Cotto is cut by the left eye. Cotto is in big , big trouble. There’s a minute left. Cotto is down again from a combination. Cotto’s corner stops it at 2:05.
Margarito is the new WBA welterweight champion.

 

http://sports.yahoo.com/box/news;_ylt=ApHm5NqylQRkv0Nwnhrsp8k5nYcB?slug=ki-boxlive072808&prov=yhoo&type=lgns

This site has the complete fight:

http://www.mmashare.com/miguel-cotto-vs-antonio-margarito-boxing-fight-video-t2158.html