The Koka project tries to see if effect inference can be used on larger scale programming. The language is strict (as in ML), but seperates pure values from side effecting computations (as in Haskell). Through the effect types, there is also a strong connection to its denotational semantics, where the effect type of each function has a direct translation to the type signature of the denotational function.
Try out koka live on the rise4fun website.
April 2012: slides for a talk I gave at Lang.Next and IFIP WG 2.16