Google announced the AdWords ads may now officially show at the bottom of the search results, if they are not shown on the right hand side.
Google has tested this in the past, most recently last month and also in 2010, 2008 and 2005.
Google said:
We dynamically optimize each search page, including its ads, to provide the best experience for our users.In many cases, we have found that displaying ads below search results fits better into the user's flow as they scan the page from top to bottom. On average, this placement performed better than side ads in terms of click-through rate in our tests.
That being said, now many are noticing that the search box at the bottom of the page is missing. I believe it was missing since Google Instant launched years ago but maybe it came back since then?
A WebmasterWorld thread has one user explaining why he thinks the search box is missing, "Gonna be ads now on the bottom of the search! Can't distract people with search boxes on a search engine!"
Again, I think it was missing since Instant - not sure why people are taking notice of it now.
Forum discussion at WebmasterWorld & Google Web Search Help.