The Smith Memorial Center is part of Portland State University and is pretty much in central downtown Portland. As of yet I haven't been able to find the exact address but typing 1800 SW Park Ave into Map Blast will get you pretty close.
Here is the best [http://www.pp.pdx.edu/FAC/Arch/maps/campusmap/netscapemap/netscapemap.gif campus map] of PSU that I've been able to find.
[Note: This is the location of the June WirelessSummit meeting.] -- AdamShand