The World Wide Web is evolving rapidly into a social networking commons. The changes in the usage of the Web are stylized as upgrades although there is no real software change called "Web 2.0" The terms are really just shorthand ways to refer to the vast changes that are happening daily. I found a really good discussion of the terms and how they are applied at the LDSTech Website.
You may be interested in learning about the new direction the Web is taking.
Read more at http://tech.lds.org/