Computer Technology Review just posted an article we contributed titled: Shedding Tiers - Creating a Simpler, More Manageable Storage Infrastructure.
First there was HSM (hierarchical storage management), then there was ILM (information lifecycle management), now their is tiered storage.
One thing we've failed to recognize as an industry is that while segmenting storage into different tiers might appear like an advantageous move economically, it is often more trouble than it is worth management-wise.
Put another way, more buckets don't necessarily make organizing any easier, and they can often make it more complicated.
Check out the full article for more details.