6. The method of claim 1 , wherein estimating the distribution over locations can involve: collecting a set of candidate locations from location distributions that the user has previously specified and/or locations that the user has previously visited, optionally excluding: candidate locations that have not been visited more than a predetermined number of times; location distributions that have not been specified more than a predetermined number of times; location distributions that were not specified during a time interval derived from the time associated with the current context; and/or candidate locations that were not visited during one or more time periods corresponding to the time distribution associated with the hypothetical context; and determining a distribution over locations from the set of candidate locations or one or more statistics of the set of candidate locations.
6. The method of claim 1 , wherein estimating the distribution over locations can involve: collecting a set of candidate locations from location distributions that the user has previously specified and/or locations that the user has previously visited, optionally excluding: candidate locations that have not been visited more than a predetermined number of times; location distributions that have not been specified more than a predetermined number of times; location distributions that were not specified during a time interval derived from the time associated with the current context; and/or candidate locations that were not visited during one or more time periods corresponding to the time distribution associated with the hypothetical context; and determining a distribution over locations from the set of candidate locations or one or more statistics of the set of candidate locations. 7. The method of claim 6 , wherein the statistics of the set of candidate locations are determined in part from the type of venue associated with each candidate location; and wherein the distribution over locations can include locations not in the set of candidate locations but related to the type of venue of at least one candidate location.