How important is a business plan?

Web Worker daily has an interesting piece which talks about the importance(or not) of writing a business plan.

Personally, if I were to form my own company, I would a have a business plan, if not for anything else, just to write down what I feel. I have an habit of writing down all the stuff I need to do ( personal/official) and I would use my business plan more as a reminder than as a bible that I would strictly adhere to. And hey, that is the first thing what the VCs want to see even though they probably never take a look at that