Zillow.com and Yahoo today formed what they are calling the "largest real estate network on the web" as part of a partnership announced today. As part of the deal, Zillow's sales force now has the ability to sell advertising across both sites. Meanwhile, for-sale listings on Zillow now appear on Yahoo Real Estate. The two companies have worked together since 2006, and they strengthened ties last year when the advertising pact was first announced.

We've speculated before about Yahoo as a potential acquirer of Zillow, and this deal certainly brings the two companies closer. But as The New York Times points out, Yahoo has been outsourcing businesses that fall outside its core strengths as part of the company's turnaround.

"One phone call can now connect industry professionals to the biggest real estate network on the web," said Spencer Rascoff, CEO of Zillow. "The launch of this partnership will simplify advertising decisions and bring Zillow listings to millions of additional users every month."

Zillow, which has raised $87 million from Benchmark Capital and others, attracted 15.7 million unique visitors last month.