15. An apparatus, comprising: a memory configured to store social signal data based on social signals published using social media accounts, the social signal data including first information that includes a content of the social signals and second information that is different than the first information, wherein the second information includes metadata; and a processor configured to: identify conversations associated with the social signals using said second information; group the conversations into clusters using the first information, wherein said grouping using the first information comprises: forming a first set of clusters that correspond to a first time; forming one or more second sets of clusters that correspond to one or more second different times, respectively; wherein, responsive to the grouping using the first information, a first one of the conversations is grouped with a second one of the conversations into a same one of the clusters of the first set or the one or more second sets, the first one of the conversations based on a root social signal of the social signals that is not explicitly linked, by the second information, with a different root social signal on which the second one of the conversations is based; identify topic distributions for the clusters by identifying probabilities for terms in the clusters; generate a context distribution from the social signals; identify candidate labels from the context distribution; generate joint distributions for the candidate labels by identifying different groups of the social signals that include terms from the candidate labels and identifying probabilities for terms in the identified groups of social signals; derive mutual information values for the candidate labels by applying the joint distributions for the candidate labels to the topic distributions for the clusters; and select topic labels for the clusters from the candidate labels with the largest mutual information values.
15. An apparatus, comprising: a memory configured to store social signal data based on social signals published using social media accounts, the social signal data including first information that includes a content of the social signals and second information that is different than the first information, wherein the second information includes metadata; and a processor configured to: identify conversations associated with the social signals using said second information; group the conversations into clusters using the first information, wherein said grouping using the first information comprises: forming a first set of clusters that correspond to a first time; forming one or more second sets of clusters that correspond to one or more second different times, respectively; wherein, responsive to the grouping using the first information, a first one of the conversations is grouped with a second one of the conversations into a same one of the clusters of the first set or the one or more second sets, the first one of the conversations based on a root social signal of the social signals that is not explicitly linked, by the second information, with a different root social signal on which the second one of the conversations is based; identify topic distributions for the clusters by identifying probabilities for terms in the clusters; generate a context distribution from the social signals; identify candidate labels from the context distribution; generate joint distributions for the candidate labels by identifying different groups of the social signals that include terms from the candidate labels and identifying probabilities for terms in the identified groups of social signals; derive mutual information values for the candidate labels by applying the joint distributions for the candidate labels to the topic distributions for the clusters; and select topic labels for the clusters from the candidate labels with the largest mutual information values. 17. The apparatus of claim 15 , wherein the context distribution comprises terms and probabilities of the terms occurring in the social signals of the ecosystem during a day.