I heard about this on Andrew Wilkow's show on Sirius Patriot Radio Thursday. This guy filming a documentary on the border and talks about how our neighbors 'patrol' the border...

http://www.conservativepunk.com/

Mexican Soldiers Cross the Border Into America
By Rizzuto

Thu Aug 07, 2008 - On the heals of this story of about the Mexican military crossing over the border and detaining American border patrol agents the other day, we've gotten ahold of some exclusive video from an anonymous film maker showing that these incursions happen fairly regularly. He has asked to remain anonymous because he is still working on a larger documentary which includes this footage.

This exclusive footage was taken in an area known to be a crossing for drug smugglers and was being patroled by a civilian border watch organization. Off duty Mexican military are often used to provide security for drug smugglers.