Hello, @dan,
Indeed the original Adaptive images script could work with NginX, but one had to do the integration and the setup manually. What our plugin does is that a) the script is totally rewritten b) it is integrated into WordPress as a plugin with settings and everything and c) the setup is automatic for Apache!
If one wants to setup NginX manually with our plugin they still can! It’s just not done automatically. In Apache it is -more or less- easy to manipulate the .htaccess file, in order to do what we want. We haven’t tried to do this automatically in NginX (at least not yet).
However, there have been other discussions in this forum on the subject that you could follow.
Cheers,
Takis