Multicast IP has been around for 20 years (!) - but only recently seen large scale use, e.g. for IPTV - there are now some examples of compelling large scale deployments which show why it is really useful. This relies on the relaxation of the old so-called "any-source multicast" to the more restricted "single-source" multicast model (or point-multipoint).
The potential for google click-thru type market research and targetted advertising should be obvious:)
If you are getting tired of reading this, and its after the cocktail hour, then
here is some advice on what to read to go with your drink.