Presearch just reached 50,000 beta users and they are on schedule to reach 100,000 beta users by the end of May. Those numbers could translate into millions of daily searches. When they start marketing their product, Presearch could hit the 1 million user mark within the next 6-8 months or sooner.
Update - as of May 28 - Presearch is now over 125K users and the community is growing daily.