I'm also attempting to set up simple captcha on a joyent accelarator,
and am running on the same problem. By clicking on the link
http://www.gogonova.com/active_rbac/registration/register, it seems like
you guys have fixed the problem. Was the problem with
rmagick/imagemagick? Does the version of the plugin that doesn't use
them solve the issue? It seems like rmagick has been added back in to
the newest version. Any help/insight at all would be appreciated.