Google have just announced that they have been doing some work to improve the way their search engine.
Here's part of their post on http://googlewebmastercentral.blogspot.com/2009/08/help-test-some-next-generation.html
"For the last several months, a large team of Googlers has been working on a secret project: a next-generation architecture for Google's web search. It's the first step in a process that will let us push the envelope on size, indexing speed, accuracy, comprehensiveness and other dimensions. The new infrastructure sits "under the hood" of Google's search engine, which means that most users won't notice a difference in search results. But web developers and power searchers might notice a few differences, so we're opening up a web developer preview to collect feedback."
What we won't know yet is if this will seriously change the way websites rank today, so we'll keep a careful eye on things.
You might want to visit the sandbox and try out some of your most important search terms and see how your website fares.