For navigational queries, which usually have a single relevant answer, Google experiments with adding a link to the first search result at the top of the suggestions list. Google Chrome already implements this feature and it's likely that it will be added to Google's homepage as well. Other experiments include ads and results from specialized search engines, but they don't seem to be useful.
The other two experiments continue an already obvious trend of expanding and enhancing the snippets. This time, instead of automatically detecting information from the unstructured code, Google asked some review sites to include special tags for ratings, summaries and other metadata. Yahoo has a service called SearchMonkey that encourages web sites to surface structured data using microformats and embeddable RDF.
The third experiment solves the problem of finding a long web page in the search results that includes the answer to your query in a subsection. For example, Wikipedia articles are structured in sections and subsections, each one having a permalink that uses named anchors, but Google doesn't send you directly to the right subsection. This experiment includes a link that lets you "jump" to the part of the page that includes your answer.
You can already see some of these ideas in Google Chrome, Yahoo SearchMonkey, Google Mobile search and Live Search's results from Wikipedia.