Google search's playground, also known as SearchMash, has changed from last month.
Each search result page has 3 sections: web search, image search and results from Wikipedia. The sections can be minimized and you can hide the snippets from web search results. The results from image search are placed at the bottom of the page, while the first three results from Wikipedia can be shown if the user expands Wikipedia section.
If you click on "more web results" the next 10 results are displayed instantly, as Google prefetches them.
We can expect to see more sources mixed in one page, some of them by request, some contextually. The idea of having a single result page is not new, but it's a good opportunity to integrate Google's different kinds of searches.