The American Institute of Architects 2009 National Convention and Design Expo is taking place this week in San Francisco.
Their "Virtual Convention" is free:
(We didn't see any prefab or modular companies listed, though several of the products may end up in prefab homes.)
where: San Francisco, CA
location: The Moscone Center
date: April 30 - May 2, 2009
cost: $525 members, $875 non-members, free online access to exhibitors
notes: on-site registration is now open