You'll want a 2 to 3 page executive summary. This needs to get across the high-points of the plan, to motivate the VC to keep reading.
So think not only about content but also about format. Make it easy to read.
Remember that you'll want to be able to extract your executive summary, put a cover sheet on it, and use it as a stand-alone document. So it needs to cover all the high points. But don't try to cover everything that's in your business plan -- you can't in a short document.
Remember, the goal of the executive summary is to create enough interest that the reader wants to learn more.