The term "Web 2.0" gets thrown around a lot these days. From my vantage point it was originally used to describe how the internet is entering a new paradigm. One that moves away from closed silos that hoard information into a world where information is shared and communities are built through interaction. Then the term expanded to include the technologies that aid online community; Things like RSS and AJAX. And now "Web 2.0" is used to describe whatever is new, whatever is cool. The term has almost completely lost its meaning.
But that original definition, the one about creating communities and online interaction, is what CommunIT.ca is all about. We help nonprofits and progressive businesses develop communities and engage people.
For a detailed history of "Web 2.0" take a look at this short movie courtesy of Jeff Utecht.