Google is beta-testing a new search engine called SearchMash. It's actually the same Google search engine but with a different user interface. According to Google, it's very much an evolving site. Here's a brief summary of what I've found out about it by using it a little:
Searching: The search page is totally basic stripped-down Google, just a search box, clean and elegant. There's no advanced search page or preferences. But you can use the same Boolean operators as on Google, and the same field limiters (like site:.edu) - although I found that the "filetype" limiter doesn't work on SearchMash which is a drawback.
Results: The real difference between SearchMash and Google is how your search results are presented. You get a list of results somewhat similar to Google. But they are numbered, and they are more compact. There are no ads or sponsored sites (at the moment). And the usual list of webpages is on the lefthand side of the page, but on the righthand side of the page you can see what search results were found in Images, Blogs, Videos and Wikipedia, which I found useful in some cases. A nice feature is that when you go to look at the next page of results the first page results are still displayed, so that it's like scrolling infinitely through the search results.
I read about SearchMash on the SearchEngineWatch blog, and the writer contacted Google to ask about SearchMash. Google replied that "SearchMash is an experimental search site operated by Google. The goal of SearchMash is to test innovative user interfaces in order to continually improve the overall search experience for our users." When you use SearchMash, you can give feedback to Google about how you liked it right from the results page.