Robert Scoble, author and technology evangalist blogger, notes with emphasis that the suggestion that Twitter and several other popular sites got funded without a business plan is just plain wrong. "If you REALLY think you can get funded without having a business plan you're probably smoking something illegal." Planning is about goals, commitments, accountability, not just a document.
It's about time somebody pointed that out. It should be obvious. A plan is not just a document, but much more important, a plan, as in a plan that sets objectives for the long term and steps to achieve those objectives, and process to track steps, and analysis of cash flow implications, resources required, and focus on key points. You may be able to get financed without presenting to investors a PhD quality coil-bound formal; but that doesn't mean you don't have a plan.