When you've got an Internet connectivity problem, the last thing you want to do is hang on hold for hours on end. Internode is trying to help consumers sidestep that issue with a continuously updated online record of call waiting times.
The service (described with that always deceptive beta label) updates statistics every minute. You only get a rolling 24-hour graph, so you can't pick and choose a good time during the week for non-urgent problems, but most calls to ISP support do tend to be fairly urgent anyway.
While this is a neat feature and a useful idea other organisations could adopt (as Nick suggests over at Gizmodo), in Internode's own case it's not necessarily particularly relevant.
Firstly, because Internode has a 'callback' system where you can leave your number rather than staying on the line after you've been waiting a few minutes, wait times take on a different complexion. Secondly, as someone who has rung Internode numerous times over the last year to try and get my eternally dodgy connection working, I can only recall one occasion where I waited more than five minutes (which the current graphs seem to bear out). But that doesn't mean other ISPs shouldn't try and follow suit.