This concept can be generalized to any form of property. I really think the block chain, and its ultimate use for this purpose, and the fact that you need bitcoins for all of these transactions, is the biggest asset that the bitcoin system has and will ultimately prove to be the thing that ensures bitcoin has intrinsic value.
This.
The blockchain is simply a way to reliably establish ordering among the sequence of events without relying on a trusted authority. Incidentally, ordering of transactions is the central element of a digital currency system, but it can also be used for many other things. All of them can easily use the same blockchain without interfering with each other.
Come to think of it, even alternative currencies may probably be implemented ON TOP of the Bitcoin blockchain and come with the security of 10 terahash network out of the box.