Rob Pike was interviewed by Slashdot and had this to say about storage structures:
One of the big insights in the last few years, through work by the internet search engines but also tools like Udi Manber's glimpse, is that data with no meaningful structure can still be very powerful if the tools to help you search the data are good. In fact, structure can be bad if the structure you have doesn't fit the problem you're trying to solve today, regardless of how well it fit the problem you were solving yesterday. So I don't much care any more how my data is stored; what matters is how to retrieve the relevant pieces when I need them.
Grep was the definitive Unix tool early on; now we have tools that could be characterized as ‘grep my machine’ and ‘grep the Internet’. GMail, Google's mail product, takes that idea and applies it to mail: don't bother organizing your mail messages; just put them away for searching later. It's quite liberating if you can let go your old file-and-folder-oriented mentality. Expect more liberation as searching replaces structure as the way to handle data.
Clay Shirky in his article Shirky: Ontology is Overrated: Categories, Links, and Tags, says this:
Browse versus search is a radical increase in the trust we put in link infrastructure, and in the degree of power derived from that link structure. Browse says the people making the ontology, the people doing the categorization, have the responsibility to organize the world in advance. Given this requirement, the views of the catalogers necessarily override the user's needs and the user's view of the world. If you want something that hasn't been categorized in the way you think about it, you're out of luck.
The search paradigm says the reverse. It says nobody gets to tell you in advance what it is you need. Search says that, at the moment that you are looking for it, we will do our best to service it based on this link structure, because we believe we can build a world where we don't need the hierarchy to coexist with the link structure.
Avi Bryant, however, says DontForgetYourBuckets.