On the blog, Software Engineer Sitaram Iyer and Principal Engineer Matt Cutts said Caffeine is "the first step in a process that will let us push the envelope on size, indexing speed, accuracy, comprehensiveness and other dimensions."

'Under the Hood' Infrastructure

This new infrastructure is part of the "under the hood" infrastructure, and the company said "most users won't notice a difference in search results." But it did predict that "power searches" and Web developers will notice the difference, which is why the company is asking for developer feedback.

Caffeine isn't finished yet, Google said, but apparently it's completed enough to be made available for public testing. The developer preview is available at http://www2.sandbox.google.com.

Around the Web, reactions to the new Caffeine-enhanced search engine range from not seeing any differences, to seeing faster results, to seeing fewer but more targeted results for such common searches as drugstores.

Some observers said they didn't expect the infrastructure changes to dramatically alter rankings, since it didn't change the search engine's basic algorithms. But it could lead to ranking changes in the future if the new infrastructure makes it easier for Google to add enhancements.

In the blog posting, the Google engineers said they are primarily interested in any perceived differences between the current search engine and the Caffeine-enriched one. They said this includes higher-level feedback, such as whether types of sites appear to rank better or worse in the new system, or if a given site shouldn't be showing up for a specific query.

'See How It Evolves'

The exact nature of the differences that users are expected to see were not described by Google, but any differences in how Google presents results could have a substantial impact on businesses, especially those whose traffic and sales are directly dependent on Google results.

Laura DiDio, an analyst with industry research firm Information Technology Intelligence Corp., said the Caffeine upgrade isn't currently resulting in any user-interface changes, since the rebuild focused on infrastructure.

For the moment, she said, "businesses will probably need to just see how it evolves," especially since a lot of IT departments are already challenged with the work they have to do and the resources available in a still-recovering economy.

Google is still "way ahead of the pack" of other search engines, DiDio said, but they "can't rest on their laurels."