I finished writing the first draft spec of PSGI on my 10 hour flight
from SFO to NRT. It's mostly a clone from Ruby's Rack with lots of
insightful observations from Python PEP333, but obviously changed a
couple of things so most Perl applications can easily implement. There
are things that need to be discussed / thought before making it a
final, so i dumped them in PSGI/FAQ.pod.

Specifications:
https://github.com/miyagawa/psgi-specs/

Feel free to comment on it via this mailing list or IRC channel
#http-engine at irc.perl.org.

But read the FAQ first, and come up with your real concern as a
developer, not just to criticize or nitpick.

Oh, and one thing that might need clarifications but not yet specified
is psgi.async support. We do have a working code in touhirom's psgiref
on psgi-spec-0.1 branch.
http://github.com/tokuhirom/p5-psgiref/commits/psgi-spec-0.1

Useful links:

PSGI Implementations:
http://github.com/miyagawa/Plack
http://github.com/tokuhirom/p5-psgiref

Web application adapters:
https://github.com/miyagawa/Catalyst-Engine-PSGI
https://github.com/miyagawa/CGI-Application-PSGI (not there yet, will
push later)

Original Announcement:
http://bulknews.typepad.com/blog/2009/09/psgi-perl-wsgi.html

--
Tatsuhiko Miyagawa