Share/Assign task & task status via IM or P2P
A user (boss) creates a task, and assigns it to another user (worker), it could travel through an IM or P2P protocol. A task server/tracker/repository could handle the traffic routing
User (or boss) could set up a "Report status" action(or "report tasks automatically every [update|daily|weekly]"). When Master Task is changed, it is spread through all users involved. Collisions should be accepted manually.
Tasks could be local or remote, single user (using 1 subtask for each user in case there are many users).
N Agarwala commented
I think an easy implementation method would be :
if tasks are grouped in folders with category names.
If we share using dropbox using multiple folders
and each folder is a category shared with some users
i am the boss and i have 3 employees A, B, C
i prepare a category called userA => it will store task in folder 'userA' => shared with employee A
another category 'userAB' => it will store in folder 'userAB' => shared with employee A and B