I've always been fairly ambivelent about the whole thing since I live way up in the north here. My attitude was basically "Yeah, they shouldn't be here, but wat's the big deal?" Lately though, I've been doing more research on it (from as non-biassed of sources as I can find) and have come down firmly against it. I'm all for immigration -- the vast majority of us are descended from immigrants who came here and conquered the continent -- but I'm all for documented, legal immigration. The porous border represents not only an economical drain, but a defense issue.
Most importantly: Fine the companies and individuals that hire them. Take away the financial attractiveness of the situation.
Strictly enforce a no-welfare, no free-health-care policy for anyone in the country illegally. Harsh, yes, but it makes coming into the country legally look a lot better.
Increase border patrols. Obviously this isn't a solution in and of itself, but it would help.
The recent protests in LA really pissed me off. Most notably, the fact that the Mexican flags in the crowds outnumbered the US flags. Let me get this straight, you're protesting because you want to be treated like American citizens...and you're waving the falg of a foriegn country? Makes it seem more like an invasion (to borrow a redneck reactionary word) than anything else.