new terms for existing technologies

Discussion groups have been around since before the web (they were
called "bulletin boards").  You could access them through gopher before
http existed.  Wikis are just bulletin boards that are organized more
randomly (less by thread).  Blogs are just server-based authoring
through a browser with a limited number of pages.  I would not
categorize either of these as "Web 2.0".

I fear the "Web 2.0" is being hijacked by vendors just as "Rapdid
eLearning" has been.  The terms have been distorted to fit marketing
purposes.  I would refer you to the following:
For a more practical definition of Web 2.0 as it would apply to
eLearning: http://www.readygo.com/e-learning-2.0.pdf
For a more practical definition of Rapid eLearning:
http://www.readygo.com/isd/index.htm?start_file=ele02/01ele02.htm
(Note that the eLearning portions are part of a larger course that has
next/back buttons, tables of contents, and other links.  Also, if you
start from http://www.readygo.com/isd your responses to test questions
are tracked.  Like a Wiki, but with tracking and navigation.  This was
built and is maintained using the ReadyGo authoring tool.)