Reads ups on its, he says.
"Web 2.0" refers to a perceived second generation of web development and design, that facilitates communication, secure information sharing, interoperability, and collaboration on the World Wide Web.
(Emphasis on the subjective mine.)
Design, no; communication, half-way; secure info exchange, no; interoperability, no/barely; collaboration, a bit.
Web 2.0, lacking a spec or formal definition, is just whatever anyone sees as different online pre-2005-ish an post. PerlMonks, to me, doesn't even remotely qualify.
Which is not a critique of the site at all; just the proposed taxonomy. ELISHEVA, our blossoming culture maven, had a lot of thoughtful things to say keeping with the grain of the OP, though, which was nice to read and made the thread.