Co-op is a program that some colleges offer in partnership with companies. Basically, you take all your courses for 1 semester in the summertime. The following fall, you go work for a company for about 6 months. It's similiar to a summer internship, except the duration at the company is usually longer.
There are some advantages to this. Sometimes because summer internships are short (2-3 months), you get stuck doing menial tasks that doesn't really help. Co-op programs usually have a dedicated assigned task.
MIT and some of the Ivy schools offered this. I didn't do it but I wish I had, because some of my classmates who did had a lot more opportunity when they graduated. Not sure about the UC schools, though I would assume so (plus UC schools in engineering tend to have great relationships with companies to provide research and projects during normal schools).
Personally, for engineering, in hindsight, I really don't think it matters between the top UC's, or Ivy, or Stanford,etc. In fact, with the exception of Stanford and MIT, I think in some cases top UC's schools have better engineering programs than Ivy's, mainly due to all the corporate partnerships. What counts more is experience in the long run. My motivation for going east was just wanted because I wanted to get out of CA for 4 years.
