Tonight 7:00 on ESPN2, I know there is a C's game on against this game, but it is definitely worth recording and watching immediately after. Despite this being a friendly, these games are always heated, the two teams do not like each other and neither do the fans. It's in Colombus Ohio, so USA has home field, but you can expect to see a fairly even division of the crowd between US and Mexico supporters.
I checked the US soccer website and it looks like most of the top players are there, not sure about Mexico, though they usually take these games very seriously. If you are a fan of soccer, or are interested at all and want to check out a game, make sure not to miss this one.