The first change it is bringing is new ways to generate associated searches. Google's Ori Allon, Technical Lead, Search Quality Team, explains, "For example, if you search for [principles of physics], our algorithms understand that 'angular momentum,' 'special relativity,' 'big bang' and 'quantum mechanic' are related terms that could help you find what you need."
I performed a few tests to see how this worked. The first search I conducted was for "tube amplifiers". The main results were mostly informational web sites on how vacuum tube amplifiers work. At the bottom of the page was the Searches Related to: Tube Amplifiers. It listed "vacuum tube amplifiers," "guitar tube amplifiers," and several other search terms that combined different variations of things associated with tube amplifiers.
I also performed a more detailed search for "iPhone developers organization". There were eight associated results, each of which offered alternatives to my initial search.
Google also says it will provide better results for longer queries. The more words you type into the search field, generally the more scattered your results are. Google hopes its improvements will refine results for longer searches.
Another improvement being offered by Google is longer snippets on the results page. Google's Ken Wilder, Snippets Team Engineer, explains, "When you do a search on Google, each result we give you starts with a dark blue title and is followed by a few lines of text (what we call a 'snippet'), which together give you an idea of what each page is about. To give more context, the snippet shows how the words of your query appear on the page by highlighting them in bold."
By providing more information in the snippet, users will better be able to determine what's on that search result and whether or not it might be useful. In the searches I performed above for "tube amplifiers", I can't say with certainty that the snippets were longer than they were yesterday. Most results has two lines of text underneath it.