Building your startup with a goal of getting acquired is foolishness anyway, in my opinion. Smart people disagree with me on this, but I'll make my case in two points:
Big companies don't want to buy startups that want to get bought. Instead, big companies buy startups that have built something of value that they decide is important to them.
You can't possibly guess what things of value big companies are going to want to own in one or two or three years. The world is changing too fast -- witness the Microsoft hostile bid for Yahoo itself! -- and besides, big companies are Moby Dick and you can't understand the reasoning behind their decisions anyway.
Combine those two points with the fact that no big company buys that many startups each year anyway, and it's easy to see that the odds of you successfully anticipating something that a big company is going to want in the future and then actually selling your company to them -- as your strategy -- is a very risky proposition that is highly prone to failure.
And in fact, in my experience, most startups that start with the goal of getting bought, fail.
The formula for success in startups is the same today as it's always been, and it will be the same post-Microsoft/Yahoo:
Build something of value -- something that people want, and something that will be profitable at the appropriate point -- and the world is yours.