Google rarely places any sort of advertising on their homepage. Only with natural disasters or global relief causes. There was actually a rare occurrence in which they went against their code and placed a link promoting something… it was towards their Android-powered Google Nexus One was officially announced. It seems they have done the same this time around with the new Nexus S. You’ll probably end up on Google sometime today… it’s there in the middle of the screen with a flashy “New! Introducing Nexus S, the latest phone from Google”.
Source: Google
News 
News 
News 
News 