The development version source code is here: http://trac.gisclient.net

# for GisClient 3 (Beta)
svn co http://gisclient.net/svn/gisclient/trunk gisclient-3.0

# for GisClient 2.1
svn co http://gisclient.net/svn/gisclient/branches/2.1 gisclient-2.1