Previously the versions had code names named after locations. Hekaton isn't a version (SQL Server 2014 is a version), hekaton is a feature and the features often get their own code names (eg xVelocity).

The word is greek, e?at?? it means one hundred. The feature was so named because their goal was a 100x speedup. Haven't got their yet, but this is v1.

http://www.thefreedictionary.com/hundred-