- Did somebody explain to you what Big Data is ? Not to mention Cloud Computing, Tripple Stores, semantics, ... And did you find two people that gave you the same explanation on all of those ? Really ? Can I have their email-addresses please ?
- Did somebody explain to you what map reduce is ? You are going to use it to query your data ! Did you look it up ? Do you understand the mathematics ? Really ? Oh, you're a PhD Mathematics ... figures.
I also want to add that a lot of this is far from new. Everybody that ever used LDAP knows that a key-value-store has been around forever. And while a graph database (the thing Facebook is build on) is super flexible and a hell to query in a performant way - can you hear Kerching! too ? - it's roots lie in the CODASYL findings of 1969 (remember IDMS anyone)... yes, the year a man put foot on the moon. Server- and database clusters with quorums ... been there and done that with HP systems and Oracle as early as 2001.
Personally I play with it all (watch this space for upcoming technical posts) and I see the benefits and the drawbacks of many a hype. For me they are all tools to get the job done, the job defines the tool, not the other way around. Remember that before you buy into one ! And the day the new Edgar Codd stands up and starts bringing down the towers of complexity once more ... lets give her/him a Noble Prize !