The only fence that has any chance of working is one that is closely watched (guarded). Mexicans are totally capable of building ladders and tunnels, so you can't just build a fence and forget it. Even a mine field can be defeated with a little ingenuity.
The only conclusion I come to is that we're going to have to put a lot of boots with guns along the border in addition to some kind of wall, or fence to slow the hoards down a bit. On this side of the fence, we'll need some type of incentive to not hire illegals and not provide benefits of any kind. Don't hold your breath for this to happen.
On the other hand, President Bush is exactly correct that we need an effective guest worker program for the agricultural sector of our economy. There are farmers in the area of the country where I live that are desperate for workers to harvest their crops. It is simplistic to say that if they paid more, they would have plenty of workers. Yes, they might attract some workers, but then they'd be faced with a product that they couldn't sell for a profit.
Any guest worker program that will not revert to and exacerbate the problems that we are plagued with now, has got to restrict who the guest workers can bring along and require them to leave the country after a specific time. A big monkey wrench in the whole thing is our own citizens who are often too willing to sympathize with illegals and even marry them to keep them here. Yeah, just wait for this to get fixed.
All that said--pi## on it--just shoot the barstads.