SEO or search engine optimization is, basically, using keywords to gain a high ranking in Google's search results, aiming the "coveted" first page that comes up. A change like Google Caffeine could throw SEO masters into a tizzy.
Google hasn't just throw Caffeine into the wild, though. They've created a preview where developers and webmasters can try it out, and give feedback.
The Google Caffeine preview is available at http://www2.sandbox.google.com/. What Google wants, at least for now, is feedback on the differences between the current results given by its search engine and Caffeine.
It is unclear how long the Google Caffeine test phase will last, so those interested in giving feedback should probably hop onto that URL and start testing know. Here's what Google says in their blog post:
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.
Some parts of this system aren't completely finished yet, so we'd welcome feedback on any issues you see. We invite you to visit the web developer preview of Google's new infrastructure at http://www2.sandbox.google.com/ and try searches there.
Right now, we only want feedback on the differences between Google's current search results and our new system. We're also interested in higher-level feedback ("These types of sites seem to rank better or worse in the new system") in addition to "This specific site should or shouldn't rank for this query." Engineers will be reading the feedback, but we won't have the cycles to send replies.