8. A computer-readable medium having stored thereon computer-executable instructions for performing a method of analyzing a plurality of search sessions to identify intent-based clusters therein, each session comprising at least one received query from a user and a corresponding set of returned search results, each set of search results including or referring to at least one piece of content, each cluster representing a group of similar search sessions that are perceived as representing a common intent of a plurality of different users and that can be mapped to a common set of search results, the method comprising: identifying for each search session each received query thereof, the corresponding set of search results, and whether any particular piece of content of the search results was acceptable to the user as responsive to the corresponding search session; and grouping search sessions into clusters based on the commonality of judgments of a plurality of different users about a search result that is common to the user's respective search sessions, wherein each of said clusters includes search queries and search results, such grouping comprising: constructing a table with a plurality of entries therein, each entry representing a unique pair of sessions such that each session is paired with every other session a single time in the table; judging, for each entry of the table, a strength of commonality of the pair of sessions thereof; reordering the entries in the table according to decreasing strength; and reviewing each entry in the table as reordered to decide based on the judged strength thereof whether to assign each session thereof to an intent-based cluster.
8. A computer-readable medium having stored thereon computer-executable instructions for performing a method of analyzing a plurality of search sessions to identify intent-based clusters therein, each session comprising at least one received query from a user and a corresponding set of returned search results, each set of search results including or referring to at least one piece of content, each cluster representing a group of similar search sessions that are perceived as representing a common intent of a plurality of different users and that can be mapped to a common set of search results, the method comprising: identifying for each search session each received query thereof, the corresponding set of search results, and whether any particular piece of content of the search results was acceptable to the user as responsive to the corresponding search session; and grouping search sessions into clusters based on the commonality of judgments of a plurality of different users about a search result that is common to the user's respective search sessions, wherein each of said clusters includes search queries and search results, such grouping comprising: constructing a table with a plurality of entries therein, each entry representing a unique pair of sessions such that each session is paired with every other session a single time in the table; judging, for each entry of the table, a strength of commonality of the pair of sessions thereof; reordering the entries in the table according to decreasing strength; and reviewing each entry in the table as reordered to decide based on the judged strength thereof whether to assign each session thereof to an intent-based cluster. 14. The medium of claim 8 wherein the method further comprises mapping each cluster to a common set of search results that is believed to satisfy the common purpose of such cluster so that all queries with the same common purpose map correctly based on such cluster.