Just as Microsoft is becoming a popular destination for former Yahoo search engineers and executives, eBay appears to becoming one for ex-Microsofties.

Microsoft's Hugh Williams, who played a key role in the company's new Bing search engine, has left to join eBay, as first reported this week by Silicon Alley Insider's Nicholas Carson. Our calls to eBay this week haven't been returned, but PaidContent.org's Joe Tartakoff confirmed with Williams that he will be leading the company's search development team.

What's interesting is that eBay already employs two former Microsoft search executives, Christopher Payne and Dane Glasgow, who joined the e-commerce and online auction company when it acquired Positronic, their Seattle-based startup, earlier this year.

These moves tend to happen in clusters, as people who join a company recommend former colleagues as potential hires. On the surface, the hires might seem an odd move by eBay, given the fact that Microsoft's Live Search engine didn't exactly light the market on fire.

But Mary Jo Foley quotes an anonymous Microsoft insider calling the departure of Williams a "huge loss" for Microsoft's search team.

Williams' LinkedIn profile says his team at Microsoft was responsible for key elements of the newly launched Bing search engine, including "the development of all user-facing web search relevance features, including the left-rail explore pane (with its "table of contents"), navigational query treatments, query-biased summaries, "deeplinks", related searches, and whole page results relevance."

He also managed the company's Powerset team and also managed development of search features in Internet Explorer 8 -- which happens to count a certain online auction company among its key partners.