del.icio.us director is an interesting service that has wide ramifications for the web service world.
How are these techniques going to change the web service landscape?
The current landscape is a complex tangle of specifications concerning identity, authorisation, orchestration, transactions, messaging etc. (see here and here). The assumption is that all the pain of these specifications will be handled by the platform vendors who will build new platforms for new applications. The cost of entry into this world is high in both time and money.
The result has been a transition from data-mobility to code-mobility. Rather than submitting data to a web service and getting results, the model is to download the required behaviour and apply it to the data which may be local or remote. The data can be dispersed across any number of specialised stores. The informative diagram halfway down the director page illustrates this quite nicely: the coordination happens on the client, not on the server.