11. A computer storage medium encoded with a computer program, the program comprising instructions that when executed by one or more computers cause the one or more computers to perform operations comprising: receiving an observation, the observation including an updated piece of information about an entity and a context, wherein the context includes at least one value of an attribute describing the entity to which the updated piece of information relates; storing the received observation as an immutable observation that includes the updated piece of information about the entity having the geographic location and the context, wherein the immutable observation is not modifiable after storage of the immutable observation; matching the immutable observation with a first cluster of observations representing the entity using the context; the matching comprising: generating a query derived from one or more values of attributes included in the context; identifying one or more candidate clusters of observations responsive to the generated query; generating a respective score for the one or more candidate clusters, wherein the respective score is based on a comparison of one or more attribute values from the context and a corresponding one or more attribute values of the one or more candidate clusters; and matching the immutable observation with a select candidate cluster having the highest respective score; and associating the immutable observation with the first cluster of observations.
11. A computer storage medium encoded with a computer program, the program comprising instructions that when executed by one or more computers cause the one or more computers to perform operations comprising: receiving an observation, the observation including an updated piece of information about an entity and a context, wherein the context includes at least one value of an attribute describing the entity to which the updated piece of information relates; storing the received observation as an immutable observation that includes the updated piece of information about the entity having the geographic location and the context, wherein the immutable observation is not modifiable after storage of the immutable observation; matching the immutable observation with a first cluster of observations representing the entity using the context; the matching comprising: generating a query derived from one or more values of attributes included in the context; identifying one or more candidate clusters of observations responsive to the generated query; generating a respective score for the one or more candidate clusters, wherein the respective score is based on a comparison of one or more attribute values from the context and a corresponding one or more attribute values of the one or more candidate clusters; and matching the immutable observation with a select candidate cluster having the highest respective score; and associating the immutable observation with the first cluster of observations. 13. The computer storage medium of claim 11 , wherein the updated piece of information is a user review or a user rating of the entity.