You can keep your team aware of releases with regular communication - for example at end of daily standup you could give a 30 second summary on whats going to happen when.
Keep a whiteboard nearby with countdowns on for days to release, bugs in system etc
this could be the same whiteboard displaying your user story progress.
Also using Scrum methodology your development iterations should all be the same length so your developers should become used to a regular release cycle.
For a particular task, if your working with hours then you should get your task updated daily with time remaining. It should be emphasised this is a daily task and shown why its important ie - show the burndown graph at end of daily standup.
On software TFS has time remaining/estimated for tasks.
I wouldnt recommend being so exact as having timers on desktops, I dont see how they will work without manual intervention. Which would be open to inaccuracies. I tend to jot down a ticket numer or a few words describing what I'm doing then update each day.