For anyone who hasn't heard, Microsoft has a new plan to gain search market share which is to share the wealth.  Basically they will pay you "cash back" every time you use Windows Live Search to find a product and then buy that product.  Here's a quote from Techcrunch that pretty much sums up the situation...

Google’s search dominance is growing, and everything Microsoft has historically thrown at them has done nothing to slow them down. This new approach is both desperate and brilliant. Desperate because Microsoft is giving away most of the search revenue to get market share gains. Brilliant because they have such a small share of search revenue today that they have little to lose, and they are hitting Google hard in their core business.

I also think this is brilliant but for a completely different reason. 

Though I'm not personally a fan of Live Search I know many people who seem to think its as good as Google.  It certainly isn't dramatically worse.  So the question really isn't a technical one at this point.  Google essentially has two things keeping them as the market leader right now. 

1.  Marketing: This is the obvious one, Google's name is synonymous with web search at this point. 

2.  Familiarity: This is the less obvious point.  My theory here is that even if Microsoft produced dramatically better results people would still think Google is better because they are so familiar with that experience.  Think of the people who still insist the sound quality on Vinyl is better than a CD and you'll start to see what I mean.  Except in this case, unlike Vinyl vs. the CD, Microsoft can never scientifically prove to people that their search is more effective.

These two things are a powerful one/two punch for Google.  They basically mean that people will always go to Google first and will always think Google results are better even if they aren't. 

What Microsoft needs right now is a way to lure Searchers to them and get them to use Microsoft search long enough to grow accustomed to it.  Paying people is as good a way as any to accomplish that.