also referred to as Web 3.0, Linked Data, Semantic Web is covered in this very informative post on ReadWriteWeb.
There has been a lot of discussion for quite some time, mostly in tech circles on the topic of what is coming next on the web in terms of developments that will make it a smarter web than it is today. Unfortunately the focus often is on the terminology and the dislikes expressed by some about the term web 3.0 when it should be on what is just a phase in the constantly developing web and the advantages the changes bring about. The objective is to make the web more intelligent and the tools to achieve it are to be found in the areas described in RWW article. The public using the web will not care about what the new phase is called or how the underlying structure is built but in how it improves their experience in the use of the web for whatever purpose they chose.
What is obvious to me is that the developments happening in this area will have an impact on how travel is planned, researched and booked on the web over the coming years as more sites are launching that take advantage of the underlying tools. It should be an exciting new phase, whatever name it is called.