1. A method for identifying high-value information in data streams, comprising: at a computer system including a plurality of processors and memory storing programs for execution by the processors: receiving a plurality of filter graph definitions, wherein each filter graph definition includes a plurality of filter nodes arranged in a two-dimensional graph defined by a plurality of graph edges, each filter node being configured to accept or reject an individual packet in a data stream based on content and/or metadata information associated with the individual packet; preparing the plurality of filter graph definitions for execution on the plurality of processors; in response to receiving a data stream with a plurality of packets, distributing the packets to inputs of the plurality of executable filter graph definitions; and identifying, using a respective executable filter graph definition, respective ones of the packets with high-value information according to the respective executable filter graph definition, based on parallel execution of the filter nodes included in the respective executable filter graph definition.