Generic Messaging System

There should be a simple, reusable, recognisable way of providing messages to the user.

So, things like "Saved that Event Time". Will be instantly visible. They should appear in the same place, and be keenly distinguishable from the rest of the page.

It should also facilitate boxes which are persistent, say telling the user something that's changed on that screen or suchlike, and allowing them to dismiss it by clicking a "hide" link.