Membership in WPA extends from July 1 to June 30; applications for 2008-2009 closed on March 15 and will be available again in a few days. Registration for the WPA meeting, the Terman Teaching Conference, and the Statistics Workshops will be open at the Portland Marriott Downtown Waterfront on April 23-26.
Detailed information on the convention is available here. You may also search the convention program.