A large portion of the web 2.0 and web 3.0 references that you see are nothing more than marketing hype where the person who wrote about it doesn't even know what web 2.0 and web 3.0 actually are. Yes such things do actually exist even though most of the references that you see to them are actually just web 1.0 pages prettied up a little and relabelled to pretend that they are using the new technology.
One of the biggest problems is that both web 2.0 and web 3.0 have nothing whatever to do with how a web page actually looks but those sites that started using the new technologies also revamped the appearance of their sites at the same time and others have copied that change of appearance thinking that they are therefore using the new technologies even though their site still continues to really function the old web 1.0 way. So a lot of the people claiming to use web 2.0 or web 3.0 are making those claims without their even realising that what they are claiming isn't true.
So what exactly are web 2.0 and web 3.0?
Web 3.0 is the semantic web. This involvea a whole range of mostly back end technologies mixed with some front end technologies such as RDF, N-Triples, RDF/XML, RDFa, SPARQL, Freebase, OWL, Protege, microformats, and Sesame that basically set up an extensible system where the semantics of new elements added to the web site can be catered for within the existing structure of the site rather than needing to redesign the site to cater for the new elements properly. The biggest hurdle that web 3.0 faces is that the front end components such as RDF function in current web browsers but mean that a page written in HTML 4.01 will not validate. This technology can only be properly integrated into the web where XHTML is used in place of HTML. Since front end developers are tending to move away from this a dichotomy between front end developers returning to static web 1.0 pages and back end developers embracing the full web 3.0 experience is a real possibility.
This article written by Stephen Chapman, Felgall Pty Ltd.