It goes back to the specialist vs. generalist question. An MBA experience will help you become more of a generalist, you will interact with people who are different from you and solve problems differently. It will also open up career options you may not have today, hedge funds, investment banks, consulting - some of which are intellectually interesting and pay well. Even if you decide to do a startup later, you will have friends working at VCs & operating companies that you can get help from.

If on the other hand you have decided that you want to live the rest of your life as a hacker, maybe it is not such a good idea. In any case, don't consider schools beyond the top 5 (Stanford, Harvard, Wharton, Chicago and maybe MIT).