A large classified web-portal like Google Real Estate will initially attract individual sellers who have a lot to gain from paying for the advertisement (i.e. selling their house). Free listing will ultimately result in both individual sellers and estate agents posting the same property and will cause confusion for Google who will not want multiple listings of the same property.

Estate Agents will probably not want to pay for listing of a property initially as they have their own websites, which are more focused on the area that they specialise in. However, an increase in competition by individual owners selling their property on Google Real Estate without going through an agent, could result in real estate agents around the world throwing spanners into Google Real Estate in an act of revenge.

Real Estate classifieds are one of the largest sections of classifieds and agents can list multiple listings but if Google adds free listings for individual owners this many cause agents to move to other search engines, also there will be multiple listings that will take up a lot of extra server space

The US real estate market is remarkably inefficient, and a number of companies benefit tremendously from that. In the US, real estate commissions are higher than in most countries. Thus improved information flow will reduce inefficiencies in the market and ultimately cut brokers' commissions or eliminate them entirely. Effective search for real estate listings combined with Google Base would allow home sellers to list properties directly with Google for no fee and Google has already integrated its real estate search with Google Maps.

The same is being done by many conglomerates recently, Tesco the supermarket chain has announced plans to launch similar in of England with a lot of backlash from local agents.

A great article forecasting the future market trends, and a must read for any savvy business person.  Knowing what google is intending to do in the future is very valuable information.

Accoring to Google, 56% of searches for things related to Real Estate take place through their search engine, so it was only a matter of time before they got involved.  That said; Google entering the arena doesn't mean that Trulia and the other start-ups are doomed.  They just need to reinvent themselves to take advantage of the new tools that Google is offering.  The API's for Google Base and Google Maps are extremely robust, and give webmasters access to free, dynamic content which will help them attract and retain users.

We added Google Base to our listings site and have found it be a great resource for users.  We are in the process of integrating Google Base listings with a Google Mashup.

The idea of the giant MLS is difficult because real estate is a localized field people can use as a resourse but I feel will go with the local agent to negociate a deal. Property purchases are a big deal for most people and they want someone to hold there hand during the process.

Google Base, should it take off outside the US in any meaningful way, will hurt all real estate websites. What we might encounter is that real estate agents, having spent years in finding and building links to their sites to gain high placement on Google, will have done all this work for nothing. Most people choose to use Google as their main search engine but Google Base could be the new god of real estate search, although it is mainly US-based at present.