Microsoft is inking a deal to run its search results and keyword-linked ads on Facebook, CNBC reports. Make no mistake: Facebook employees share every bit as much disdain for Microsoft's lame Web efforts as the rest of Silicon Valley, despite the company's $240 million investment. So this news is unwelcome, and painful. But inevitable. What caused it?Facebook's slapdash decisionmaking about ad placement on the site, a direct result of CEO Mark Zuckerberg's endless dithering on the subject in the process of redesigning, led to the Microsoft search deal. In the end, Facebook decided to kick Microsoft's tacky banners off its homepage and users' profile pages, in favor of its own targeted Social Ads. That was a violation of Facebook's advertising agreement with Microsoft, of course, requiring a renegotiation of the deal. Microsoft, of course, was ready with its quid pro quo: Search advertising, a market Facebook has yet to tap, but was likely to eager to try to explore itself. Instead, it's running Microsoft search results, and Microsoft search ads, both of which are considerably less attractive than Google's because they draw a smaller base of users and advertisers. A hard lesson for Zuckerberg: Every decision has consequences, and pursuing his whims has costs.