Google’s agreement with Twitter to use its Tweets in the results has expired, leading to Google Realtime Search no longer functioning.
Google had an agreement with Twitter since October 2009, to include their updates in the search results through a special feed. This agreement has now expired and so far has not been renewed.
Google Realtime Search had used content from other services and not just Twitter. These results included Facebook ‘Fan Pages’ updates. However, Twitter was the most dominant.
Bing Social Search still has a deal with Twitter, whilst the search engine Topsy still has a backlog of Twitter updates on the web.