We've just launched a major update to Basecamp that introduces responsibility assignment for todo items and new responsibility screens for both todos and milestones. This was an interesting feature introduction.
At first glance, I thought it conflicted with one of our dear mantras that Project Management is Communication. I saw this initiative pulling us towards the Control and away from Communication. As in managers would use the new overview screens to assign blame (you still haven't done X, Y, and Z) and spread general mischief.
But as we talked more about the feature, I realized how that fear of misuse was dwarfed by the communication potential. First of all, we made it so that every employee could see what any other employee had on their plate — not just the administrators (who are often managers).
Using it as such, it's a great tool to enable employee-to-employee collaboration. You have an idea of whether now is a good time to disturb or talk about that feature you've been working on (because Pam is working on something similar). Or if Paul has a light load, you can arrange for a swap on some items.
At the same time, it's a really useful tool to communicate upwards that "there's just not enough hours in the day". If your todo list is already full, it's pretty hard as a manager to be oblivious to that fact and assign an even heavier load with your head in the sand. Same goes for the milestones: "If we need to get this done by Friday, maybe I shouldn't also be in charge of sending out 100 envelopes".
So despite the potentials for misuse, I'm generally pretty happy about how this turned out. Especially the new todo list where you can see everything that you need to do across all projects.