Google Realtime Search, the once company-lauded realtime search index featuring tweets and as-it-happens updates, is temporarily defunct.

The realtime search option has disappeared from the search results sidebar, and the standalone Google.com/realtime product returns a 404 error page.

Realtime search was suspended after Google's contract with Twitter for access to the full feed of public updates passed its expiration date on July 2, 2011, according to information Google shared with Search Engine Land. The original Twitter search agreement dates back to October 2009.

"While we will not have access to this special feed from Twitter, information on Twitter that’s publicly available to our crawlers will still be searchable and discoverable on Google," the company said Monday. "Our vision is to have google.com/realtime include Google+ information along with other realtime data from a variety of sources."

It's not yet known if Google is negotiating with Twitter on an extension to the original agreement, although a reworked Google Realtime Search product is in the works.

A Twitter spokesperson added, "Since October 2009, Twitter has provided Google with the stream of public tweets for incorporation into their real-time search product and other uses. That agreement has now expired. We continue to provide this type of access to Microsoft, Yahoo!, NTT Docomo, Yahoo! Japan and dozens of other smaller developers. And, we work with Google in many other ways."

Google Realtime Search started with Twitter search results and quickly expanded to include Yahoo Answers, news articles, MySpace updates and public Facebook Page updates. A slew of social services, including Quora and Gowalla, were later added to the product. These other social search features will continue to exist.

Update: A Google spokesperson added that the team is "exploring how to incorporate our recently launched Google+ project into this functionality going forward, so stay tuned. Our vision is to have google.com/realtime include Google+ information along with other realtime data from a variety of sources."