By far the most valuable thing I take away from university is not the classes, but rather the experience. As a student you get a lot of leeway to screw up and learn - even interning at large, private corporations. This has helped me in my life (and my career) more immensely than anything else I've ever learned at school (most of which I doubt I will apply in a job, ever).
Secondly, the networking opportunities that you have at a university is ridiculously useful. Short of going to war together I doubt there are many forces that bind people together as tightly as the college experience. I have made many friends, many of whom are incredibly talented and will no doubt go far in life - it's a network that you can't replicate, say, studying online.
Thirdly is the name - prestigious schools, whether justifiably or not, do for some reason make you more employable in a lot of places. I know many a hacker from "lesser" colleges who can't find a job in this economy, while I had multiple offers before my final semester even started.