Basically, Google learned long ago that it couldn't exactly trust the (small, medium or large) business owner /marketer to be 100% truthful (or anything close) with the content they put on their own websites. More often then not, the marketer would include content that didn't match their products/service just to try to outdo their competitors or game google. (I know--it's hard to believe isn't it?)
Measuring backlinks became a way Google could get some third-party input on what a website might really be about as well as how much more important one site might be than another. In that measurement scheme, unfortunately, there is no handicap for new or small businesses, though I imagine if there was, every multinational in the world would be trying to figure out how they could make themselves look smaller or newer than they actually are. Of course, the link-measuring scheme was eventually gamed by marketers (we're just a bad lot, aren't we?) and Google began weighing other factors (as Nicholas links to) more heavily as a result.
Small businesses however, may get a foothold or survive in the keyword niches that don't support enough traffic for larger companies. It takes less authority (though usually just as good optimization) to rank for those niche keywords, so while a new or local company is pulling itself up by the bootstraps to get itself established, they are usually best off targeting those more locally-oriented and long-tail keywords than the more competitive ones.