EventSourcing/CQRS (Command/Query Responsibility Segregation) is gaining a bit of traction in the .NET community. There are some great presentations[1], blogs[2][3] and projects[4] related to this architecture.
"CQRS is not eventual consistency, it is not eventing, it is not messaging, it is not having separated models for reading and writing, nor is it using event sourcing."
It is gaining a lot of traction simply because it seems like a complicated and cool way to solve an uncommon problem. I fear that Event Sourcing will soon become a over-engineered hammer for the wrong nail.
If it were me, I would use CQRS principles, with a relational backend as my source model. Then when the need for scale arises, use ETL to either non-relational db or no-db for queries.
[1]: http://www.infoq.com/presentations/Command-Query-Responsibil...
[2]: http://www.udidahan.com/?blog=true
[3]: http://blog.jonathanoliver.com/
[4]: https://github.com/joliver/EventStore/