I also got my MBA after getting my BS in Computer Science and while I think I could have learned most everything we talked about by reading books, I did learn:

- public speaking because we had to do a presentation just about every other week

- how business people with little or no technology experience think and their perceptions about technology

- how to talk to the people in the above bullet about technology

- firing people because one of my groups had a member that was not pulling her own weight, and we were told to fire her from the group

I also agree that the branding aspect is also (somehow) helpful. I recently moved from Florida to SF and when I was looking for jobs you wouldn't believe how many people were really excited/impressed/whatever that I had an MBA in addition to being able to answer the tough software questions.

If I had a choice to go back and either spend $50k on an MBA or spend it traveling the world, I would definitely choose the latter, though.