I know this is a heavily hacker infested place (it's a good thing :) but, I've been asking this question to many hackers with MBAs and I get different answers all the time. I have come to the conclusion that an MBA curriculum is not as worthy as other technical knowledge, but the networking is worth it, especially if it's a top tier school. Bonus question: which MBA program would is worthy of a hacker's time, i.e. geek friendly :) Any worthy opinions?
(How I jumped to the conclusion: read a gazillion different materials from Andreessen to Bezos to bozos, became a research assistant at a top business school to see what the heck professors really think about the curriculum, and of course, talked to a few dozen MBAs across the world in different fields)
I can't say whether an MBA is worth it since I don't have one, but I can say that in my experience it's not necessary. Action is necessary. You can learn by jumping in and doing something. Some people may need teachers and curriculum for motivation/guidance, but you can find that in lots of other places as well. Networking happens after school too, but can take a bit more effort initially.
The back story in my case is I left home at 18 and moved to a new town. I was one credit shy of my high school diploma too, so technically I'm a drop-out. I lucked out and got a job as a designer/coder, and kept learning over time on the job. I did try a university course for programming, but I dropped it after a month because it sucked. I ended up starting my own software company shortly after (turned 7 this year!). I did make some good contacts in my month at school, even hired the program director as my sales guy for about 4-5 years :) I've been working on various startups since, learned a lot, and I'm launching my latest in a month or so.
So in my experience, nothing stops you from starting a business except yourself. If you're willing to learn by doing, which naturally you learn a lot on the job anyway, then I say screw the formal edu and dive right in!