Google has had access to Twitter‘s real-time “firehose” since they came to an agreement for an undisclosed sum back in October 2009. It has allowed the search giant to keep its search results looking fresh and up-to-date as well as power Google Realtime. But this deal expired on July 2nd and has not been renewed.
The reason for letting the agreement expire has not been disclosed by either party – it may be due to price or Google moving to focus more on its own Google+ social updates offering. However, even without the agreement Google will still index a great number of tweets as each tweet is in effect its own web-page – the indexing will just not be in realtime as offered by access to the firehose.