What kind of server backends would be available?
In Plack, we already support most web servers like Apache2, and also the ones that supports standard CGI or FastCGI, but also want to support special web servers that can embed perl, like nginx. We think it would be really nice if Apache module mod_perlite and Google AppEngine supported PSGI too, so that you could run your PSGI/Plack based perl app in the cloud.