How it works in some cases is that you need a GPA of 5 excluding your first year. The university boards (and honours applications need to be approved by two separate panels) realise that as a first year you're really only starting to get the hang of things...and they tend to give you a bit of a grace period based on that.
Like I said in an earlier post, if you're looking at doing honours specifically just apply anyways, there are cases where people with below 5 have been accepted, and references from tutors are accepted in those circumstances. I can't speak for other things other than honours...but having just applied and had my application go through the process I know a little bit about how it works.