11. A system comprising: a processor; a memory; a delegate module configured to delegate a task associated with an identified portion of a first data content object to a particular user; an event module configured to determine one or more events performed on content within the identified portion of the first data content object, the one or more events being performed by a first user using a data-content-object processing application; a history buffer module configured to store one or more event indications identifying the one or more events, at least one of the one or more event indications including metadata indicating first-user interaction with the content within the identified portion of the first data content object; an event notification module configured to retrieve a notification threshold condition associated with the particular user, the notification threshold condition defining criteria for determining which of the one or more event indications are relevant to the particular user and for determining based on the one or more event indications relevant to the particular user whether to send a notification to the particular user, at least one of the criteria requiring that the relevancy of at least one of the one or more events be determined based on an interaction with the identified portion of the first data content object by the particular user, wherein the interaction is that the particular user previously commented on the identified portion of the first data content object; and a criterion module configured to use the criteria to determine which of the one or more event indications are relevant to the particular user, where the relevant historical event indications are determined based on which event indications in the history buffer correspond to the identified portion of the first data object delegated to the particular user, and to use the criteria to determine whether the one or more event indications relevant to the particular user satisfies the notification threshold condition; the event notification module further being configured to generate the notification for the particular user when the notification threshold condition is satisfied.
11. A system comprising: a processor; a memory; a delegate module configured to delegate a task associated with an identified portion of a first data content object to a particular user; an event module configured to determine one or more events performed on content within the identified portion of the first data content object, the one or more events being performed by a first user using a data-content-object processing application; a history buffer module configured to store one or more event indications identifying the one or more events, at least one of the one or more event indications including metadata indicating first-user interaction with the content within the identified portion of the first data content object; an event notification module configured to retrieve a notification threshold condition associated with the particular user, the notification threshold condition defining criteria for determining which of the one or more event indications are relevant to the particular user and for determining based on the one or more event indications relevant to the particular user whether to send a notification to the particular user, at least one of the criteria requiring that the relevancy of at least one of the one or more events be determined based on an interaction with the identified portion of the first data content object by the particular user, wherein the interaction is that the particular user previously commented on the identified portion of the first data content object; and a criterion module configured to use the criteria to determine which of the one or more event indications are relevant to the particular user, where the relevant historical event indications are determined based on which event indications in the history buffer correspond to the identified portion of the first data object delegated to the particular user, and to use the criteria to determine whether the one or more event indications relevant to the particular user satisfies the notification threshold condition; the event notification module further being configured to generate the notification for the particular user when the notification threshold condition is satisfied. 13. The system of claim 11 , wherein the first data content object and a second data content object belong to a workspace object, and the history buffer module comprises a history buffer dedicated to the workspace object.