I just wrote 4 posts on some trends that are happening on the 1st SERP combined with a growing number of B2C and B2B vertical aggregator web sites that are trying to make money by adding value (along with adding more clicks) to relevant online search results. The 5th post of mine that could be included in these same trends entitled "Is The Search Engine User & Consumer Really King?" tells of Google's recently increased number of "Sponsored Links" at the top of the "Golden Triangle" on that PRIME REAL ESTATE of the 1st SERP.
The noted web site usability expert Jakob Nielsen's "Search: Visible and Simple" has a section entitled "First Results Page Is Golden". An old Excite (search engine) Study said that 50.5 % of Searchers Never Look Past the First Results Page! Google's own "Technology Overview" on their "Corporate Information" page says "By combining overall importance and query-specific relevance, Google is able to put the most relevant and reliable results first."