ACID for your NoSQL datastore; Warp: Multi-Key Transactions for Key-Value Stores (hyperdex.org)

I'm personally invested in HyperDex (the non-ACID open source portion of the project) using it for a project of my own and have been developing a set of Haskell bindings against the HyperDex client. I may also develop some Warp bindings later, but my project may not need the guarantees provided by Warp.

The Haskell bindings project can be found here: https://github.com/aaronfriel/hyhac