41. A computer program tangibly stored on a computer-readable medium and operable to cause a computer to identify a block of text relating to a topic of interest, in a system comprising a plurality of language models, including a language model for a topic of interest, comprising instructions to: obtain a stream of text comprising text segments; score the text segments against the plurality of language models to generate language model scores for the segments of text; and identify a text segment from among the text segments as a block of text relating to the topic of interest if the score of the text segment against the language model for the topic of interest satisfies a predetermined condition.
41. A computer program tangibly stored on a computer-readable medium and operable to cause a computer to identify a block of text relating to a topic of interest, in a system comprising a plurality of language models, including a language model for a topic of interest, comprising instructions to: obtain a stream of text comprising text segments; score the text segments against the plurality of language models to generate language model scores for the segments of text; and identify a text segment from among the text segments as a block of text relating to the topic of interest if the score of the text segment against the language model for the topic of interest satisfies a predetermined condition. 42. The computer program of claim 41, wherein the predetermined condition requires the score of the text segment against the language model for the topic of interest to differ from the lowest score among the scores of the text segment against the plurality of language models by less than a predetermined amount, or to be the lowest score.