Twirlip is a notifier that works via transclusion.  It does not depend on any opencore concepts, but it works with opencore.
Details about Twirlip can be found here:

http://www.openplans.org/projects/opencore/notifications-in-opencore

PHASE 1: Basic notifications in Task Tracker (complete)

* watch/unwatch a task: get emails when ever something changes on a task you are watching
* automatic task watching on all the tasks you own: get emails when ever something changes on a task you own
* automatically watch any task that you previously owned (not implemented)
* list of tasks i am watching: with ability to unwatch a task from that list //decide on level of information available from that page
* user preference setting: turn automatic task watching on/off for the tasks you own

UI PROPOSALS:

1. Watch/unwatch a task

Add feature only at task level for now.
The feature is text link "Watch this task" toggles to "Stop watching this task". (no need for redundant, you are watching this task, "stop watching this task").
note: request for a Task Tracker modification (mouna to file track ticket) --reshuffle contents of the task details view.
view revised layout TT details revised 01 .

2. Automatic task watching on all the tasks you own + any task you previously owned

From a UI perspective, same as point #1


3. List of tasks i am watching

List of tasks i am watching should be in the form of the standard table or list of things.
This should appear on the user's account page for now. Below temporary notification messages (not twirlip messages) and above the "projects you belong to" table.

Screenshot:

 

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Notes:
1. Table should a NUI style table (same as contents page), eventually will be collapsible, and paginated.

2. This "stop watching" button affects all the rows where the user checked the box on the left. 

3"unwatching" a task will make that task disappear from the list (javascript, fade out).

Todo: 

1. Add new filtering option: for users to restrict the list of notification to a single project. Print only the list of projects for which they have notifications (RP: I worry this could be confusing).
2. Table rows should be sortable by column by clicking on column name
3. Can we have an extra link on the first column so that users can sort by name of task (alphabetically) or by projects/task lists alphabetically?