Like a lot of things in life, it depends on what you want and how you want to get there. It also depends on the institution's culture (we're going to ignore GetDrunkAndParty U).

For technical and engineering pursuits, a good college is a great place to get a fast and wide overview of theory, competing technologies (or philosophies), and different specializations/tech aspects (database, programmer, ...). (I think this is why I'm more of a generalist as opposed to java or php master...)

More importantly, (a good) college puts a lot of smart, driven people in the same place and time. Going to college allows you to form important relationships with these people that can strongly affect both your personal and professional life both now and in the future. I think both Apple and Microsoft are great examples of my last point.

Finally (assuming you got a useful degree), in case all your entreprenuerial endeavors fail in the short term; a degree can net you a high paying job with a lot of free cycles to relax/regroup and get ready to start that next idea you have =)