Arhh yes. For the sake of brevity I didn't get into more detail on how I've done this in the past.
I've experimented with both using a separate project for non-engineering (to avoid the skew) but also simply including non-dev work into the velocity with the same rigor that items that offer true value get points and 'cost of doing business' (pay server bill, write documentation) are non-point-accruing chores.
I see where you're coming from. If you're tracking tasks at all, you're doing something right. However, if you use pivotal for task management, you can't estimate how much you'll get done in a day. It's not like a developer can press the start button on three features, even if they want to complete three features in a day.
Our technique is about setting out a good amount of work for the day, and trying to meet those goals. We pull few chores/bugs/features from pivotal and throw them on the board all the time.