OSCON

OSGeo and the OReilly OSCON event.

2010
From http://en.oreilly.com/oscon2010

2009
OSCON 2009, July in San Jose California, California Chapter will be managing an  OSGeo booth

2008
From http://en.oreilly.com/oscon2008/public/content/home

OSCON is the crossroads of all things open source, bringing together the best, brightest, and most interesting people to explore what's new, and to champion the cause of open principles and open source adoption across the computing industry.

'''OSCON 2008 is happening July 21-25 in Portland, Oregon. Join over 2,500 open source developers, hackers, experts, IT managers, and users at OSCON 2008. This year's convention will include 40 tutorials that go deep into open source technology and over 400 sessions focusing on Administration, Business, Databases, Emerging Topics, Java, Linux, Mobile, People, Perl, PHP, Programming, Python, Ruby, Security, Web Applications, and much more.'''

2007
OSGEO Cascadia handled the booth.

2006
Read more about OSGeo at OSCON 2006.