A great post on the 37 Signals blog.. Why not to spend too much time planning.

"Let's just call plans what they are: guesses...So next time you're working on a business plan, call it a business guess. And that financial plan? It's a financial guess. Strategic planning? Call it with it really is: a strategic guess. 5 year plan? You mean 5 year guess." http://www.37signals.com/svn/posts/1805-lets-just-call-plans-what-they-are-guesses