Hey there G,
I noticed that the latest version doesn't seem to work well with Joomla 2.5. It has issues with the permissions settings concerning components. For example, even if you set the back end to only allow "members" to view the OpenSim Registration Form, you can easily view it even when logged out. Pretty much goes for all the component's front end for users. Set for member access only, and can reach the pages via direct url regardless of what permissions settings you give it in the back end.
Just thought I would bring this up, could result in security issues as well. In Joomla 1.5, the JOpensim components, plugins, and modules followed the way Joomla was handling perms.
Thanks!
rjspence