Well it's basically Event Sourcing [1]. It's probably also worth mentioning CQRS as well. All this stuff really appeals to my functional programming side :-)

I haven't quite figured out to what extent OT is the same as event sourcing. I guess OT is event sourcing with the additional concept of translating events over the top of other events (i.e rebase).

[1] http://martinfowler.com/eaaDev/EventSourcing.html