download the plugin at [1] 
the 0.6 plugin needs some modifications, we added a modified version of the exporter called 's3o_export.py'

[1] http://springrts.com/phpbb/viewtopic.php?f=9&t=17026
[2] http://springrts.com/mediawiki/index.php?title=S3o_using_blender

