Search Engine Land: According to Twitter, users post 1,000 tweets per second, but the microblog serves 12,000 queries per second. That's more than 1 billion searches every day and 31 billion per month. By comparison, Google serves 88 billion searches per month, Yahoo serves 9.4 billion and Bing 4.1 billion.
In order to handle all that traffic, Twitter has upgraded the technology underlying its search engine. It can now handle more data and search through tweets from up to seven days in past.