2005 - Seto, Japan - Seto, Japan in Aichi Prefecture will host Expo 2005, the next world’s fair officially sanctioned by the Bureau International des Expositions. Over 100 participants have already signed up.
2007 - One Bid
2008 - Two Bids
The Bureau International des Expositions (BIE) has currently received bids from Thessaloki, Greece for 2008, Trieste, Italy for 2007, and Zaragoza, Spain for 2008.
Additionally, Phoenix, Arizona, USA may host a non-BIE sanctioned exposition during 2008. A Phoenix world’s fair would most likely be held during non-summer months given Arizona’s harsh summer climate. The Rio Selado Community Development Foundation is proposing this exposition with the hope of creating a legacy site with museums, a biotechnology center, and facilities for the state’s university system.
Bids were also considered in other cities (Taiwan; Ottawa, Canada; Abu Dhabi, UAE; Athens, Greece; Atlanta, USA; El Paso, USA; Oklahoma City/Tulsa, USA; and San Francisco, USA) for 2007 or 2008 but no additional information has become available and it assumed that there will be no bids submitted to the BIE from these cities.
2010 - Shanghai, China - The Bureau International des Expositions (BIE), on 03 December 2002, announced that Shanghai will host Expo 2010. The world’s fair will be held just 2 years after Beijing will host the 2008 Summer Olympics.
Source: http://expomuseum.com/future/