The two companies say this deal “creates the largest real estate network on the web,” and involves several elements:

• Yahoo Real Estate search will gets its for-sale listings exclusively from Zillow — including “for sale by owner” listings placed by homeowners
• Zillow will sell local and national advertising across both sites
• Zillow ad products like “Showcase Ads” and “Featured Listings” will appear on Yahoo Real Estate

Yahoo has been outsourcing a number of its properties recently in an attempt to “align products and services against the company’s vision,” as Yahoo statements often say. We’ve written previously about Yahoo outsourcing shopping search, part of its health vertical and, of course, the biggest one of all — outsourcing search results to Bing.

As Greg Sterling showed on his blog when this agreement was first announced last summer, Yahoo Real Estate was the No. 2 real estate website according to Experian Hitwise.

Current Hitwise numbers show Yahoo down in 7th and Zillow remaining third.

In the Healthline partnership, Yahoo! gains a technology partner that already provides over 90 million users a month with the most contextually relevant and clinically accurate health information available on the Internet and offers targeted opportunities for advertisers. Under the multi-dimensional agreement, Healthline will build upon Yahoo!’s existing high quality content to develop, manage and host an expanded Yahoo! Health channel that will be rolled out to consumers later this spring.

Here’s the search part:

Under the terms of the deal, Healthline’s proprietary semantic taxonomy – created by doctors and managed and continuously improved by Healthline’s medical informatics engineers – will be the underlying technology powering Yahoo! Health’s health specific search and navigation. Yahoo! Health will also feature Healthline’s clinical applications, including SymptomSearch™, TreatmentSearch™, and DocSearch™, a suite of interactive tools that empower consumers with a complete decision support platform for health.

Healthline does in fact have a superior health-specific search engine but also operates a health-related ad network, which Yahoo now becomes part of. This is a big win for Healthline. It should also help make Yahoo’s health vertical and, especially health-related search, better as well.

As I discussed when Yahoo decided to outsource much of its shopping site to PriceGrabber (following the big search outsource to Microsoft), a pattern seems to have emerged: bring in key partners to provide content and functionality in selected content areas and verticals. By contrast, Yahoo has been hiring and beefing up staffing in news, which suggests that certain “verticals” are more core than others.

We can now play the guessing game, which vertical will be next? I’ll guess that it’s going to be real estate.

This is the latest episode in a long-running battle over who controls home listings that are part of the Multiple Listing Service, or MLS. Some of the affected real estate professionals plan to ask the NAR to change its opinion on search engines at its national convention this week.

Paula Henry is one of about 15 real estate agents affected by the NAR/MIBOR decision. Like many agents/brokers, she shows not only her own listings on her web site, but also listings from other agents and brokers who participate in a data sharing agreement through the Internet Data Exchange (IDX) system. There are strict rules over how listings from other agents may be displayed. In a post on AgentGenius.com, Paula explains the one that has led to Google’s classification as a scraper site:

Section 15.2.2 – participants must protect IDX information from misappropriation by employing reasonable efforts to monitor and prevent ‘scraping’ or other unauthorized accessing, reproduction, or use of the BLC database”

(BLC is the Indianapolis version of MLS.)

After apparently getting a complaint from another agent, MIBOR consulted with the NAR and the NAR confirmed that the rule above applies to search engines. On March 27, MIBOR sent Red Door Real Estate (where Paula Henry does business) a cease-and-desist letter detailing two issues:

1. “…the National Association of REALTORS® (NAR) is in agreement with our interpretation of the policy that the above described practice of ‘indexing your Web site’ as you have called it, is a method of scraping or reproducing the data”
2. “Under IDX policy … participants have no authority to advertise those listings [from other participants] in any other way, including Internet search engines”

The C&D letter asks Red Door to either use robots.txt (actually referred to as “rebot.txt” in the letter) to block search engines from crawling the listings on their sites that belong to other agents/brokers, or to remove the non-Red Door listings altogether. In her blog post, Paula writes that additional demands were made in April requiring Red Door to remove the MLS number, street address, and other listing data from the Page Titles and Meta Description tags of pages on their web sites.

Not mentioned in all of this is the fact that Google is practically running its own national MLS database, with the same kind of search and sort options (Price, Beds, Baths, Area, etc.) in Google Maps that you’d expect to find on full-fledged real estate sites.

Real estate brokers and agents submit their own listings to Google (or they have a third party do it), so the rules about how other agents’ listings are displayed don’t apply. And it’s not just about Google; Yahoo Real Estate also gets listings from agents and brokers, and places them on highly-optimized pages that, in my experience, often rank well for popular real estate search terms.

As for Google being a scraper site, Paula Henry will be one of two real estate agents speaking to the NAR on Thursday. She says they’ll ask the organization to review and change its policy so that Google (and other search engines) is allowed to index all real estate listings from the IDX system, no matter whose web site they appear on.

Here’s a provided example in Seattle, with valuations in the upper right. And here’s the Yahoo Local & Maps blog post that explains the new functionality in further detail.

Yahoo built the service in partnership with not-for-profit GreatSchools.net. Detail pages for each school include facts such as enrollment numbers, student to teacher ratio, test score data and graphs and so on. Also included are reviews from parents who have had kids attending the school.

I tested the site for my own city (Boulder, Colorado) and found the results to be quite good.