How important is it, really, for everyone to know what everyone else is doing at every moment. I see two issues:

1) Daily stand-ups are adequate to communicate what I'm working on each day. Updates more often than that become noise.

2) The issue/task tracking system will let me see who, if anyone, is working on a particular issue. I more often care about who is working on issue X (if X is blocking me, for example) than I care about what Joe is working on right now.