I find this way more interesting to be used for storing third party data that can later be verified.
What I still dont get from this post is if the data stored and timestamped can be "big".
For example, if I wanted to store 10000 sessions per second, would it even be possible via the blockchain hash? For the sake of the conversation, lets say these are orders on a very large web store, and I want to store the price + time of the order of an item.
In your terminology, yes, the data can be "big". As "big" as you want. From your example, I think you'd be interested in what Factom are doing -
http://factom.org/.