16. A system for providing context-based task reminders, comprising: a processor; a memory; and a list authoring surface operative to receive a task item associated with a first reminder, and to parse content contained in the task for one or more task keywords; a context extractor operative to receive one or more context information data sources, the one or more context information data sources including one or more of a calendar data source, a contacts data source, a tasks data source, a presence data source, a location data source, an email data source, an Internet content data source, a social networking content data source, one or more electronic documents, a person proximity data source, a motion detection data source, a communications data source and a light sensing data source; to parse the one or more context information data sources for determining information relevant to the received task item, including parsing content contained in the one or more context information data sources for one or more context information source keywords; a context determination module operative to compare the one or more context information source keywords with the one or more task keywords to determine if one or more context information source keywords matches one or more task keywords; if the one or more context information source keywords matches one or more task keywords, then context information source is relevant to the task for determining whether a first reminder time should be revised, to determine a revised reminder for the task item based on the information relevant to the received task item; and the list authoring surface being further operative to display the revised reminder for the task item based on the information relevant to the revised task item.
16. A system for providing context-based task reminders, comprising: a processor; a memory; and a list authoring surface operative to receive a task item associated with a first reminder, and to parse content contained in the task for one or more task keywords; a context extractor operative to receive one or more context information data sources, the one or more context information data sources including one or more of a calendar data source, a contacts data source, a tasks data source, a presence data source, a location data source, an email data source, an Internet content data source, a social networking content data source, one or more electronic documents, a person proximity data source, a motion detection data source, a communications data source and a light sensing data source; to parse the one or more context information data sources for determining information relevant to the received task item, including parsing content contained in the one or more context information data sources for one or more context information source keywords; a context determination module operative to compare the one or more context information source keywords with the one or more task keywords to determine if one or more context information source keywords matches one or more task keywords; if the one or more context information source keywords matches one or more task keywords, then context information source is relevant to the task for determining whether a first reminder time should be revised, to determine a revised reminder for the task item based on the information relevant to the received task item; and the list authoring surface being further operative to display the revised reminder for the task item based on the information relevant to the revised task item. 17. The system of claim 16 , further comprising a reminder triggering module operative to set the revised reminder to occur at a second time based on the information relevant to the received task item.