I'm running Evolution 2.28.2 on Fedora 12, and have just started setting up Evolution. I've entered a few tasks (as a college student, I have plenty), and thought I remembered it highlighting tasks that were due today and tasks that are overdue in blue and red respectively on previous setups.
Reviewing Preferences > Calendar and Tasks > Display reveals that, indeed, those two colors are selected for the two conditions. However, this doesn't seem to be working.
Obviously, I can live without this, but it is a big help when you have a list of one or two hundred tasks and you want overdue and current tasks to really stand out.