Of course this has an effect. For every new service the google people think up or buy the more they want to show it off and get traffic to it. But showing off the service is s not always enough. Google Video was no success so they bought Youtube. They are not close to Facebook and Myspace with Orkut. Also I think they remember the lesson of Altavista. One of the reasons Google erradicated Altavista so quickly was that Altavista cluttered the search results with all sorts of sponsored links and services. The other main reason of course was Googles superior ranking of results.