CGI::Application offers native PSGI support. The default query object for this is CGI::PSGI, which simply wrappers CGI.pm to provide PSGI support to it.
This is a survey of how people develop and deploy Perl web applications using PSGI. Collected results will be published and discussed in my upcoming talks at YAPC::NA and OSCON 2011.
One of the fun things about MetaCPAN is that we've split the project into two main parts: an API and a front end. What this means is that if you want to start pushing your code into http://beta.metacpan.org, you don't need to run a local copy of the API. You can just git clone the front end, install your dependencies and be on your way.