Since the beginning, Riak has been a plain-Jane key-value store that pretty much didn't care what you stored in it.
That changed for the first time in Riak 1.4, when we introduced a new convergent data type, the counter, exposing operations other than just "set" and "get".
We're going even further for Riak 2.0 by adding more convergent datatypes, a whole new API for accessing them from client applications, and garbage collection to keep them tight and small.