Google Realtime Search, which incorporates results from the Twitter firehose, is down, after the company's deal with the micro-blogging site expired without being renewed.
Early on Sunday, users started seeing a 404 error message on the site.
On the company's Realtime Twitter feed, it gives little away. "We've temporarily disabled google.com/realtime. We're exploring how to incorporate Google+ into this functionality, so stay tuned," it says.
But according to SearchEngineLand, it's not likely to reappear anytime soon, or at least not in its present form.
""Since October of 2009, we have had an agreement with Twitter to include their updates in our search results through a special feed, and that agreement expired on July 2," Google told the site.
"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 says it does have plans to reopen the service, though it gives no timescale: "Our vision is to have google.com/realtime include Google+ information along with other realtime data from a variety of sources," it says.
Twitter wasn't the only provider of content for the service - Facebook fan page updates, Google News links and FriendFeed updates, amongst others, were also included. However, it was the most dominant source.
Microsoft's Bing appears to be continuing to offer the Twitter firehose.