Aha, that was it. Rated 4 out of 5 stars
So I'd posted earlier that the plugin wasn't working - the trick was right-clicking on the Add-ons bar, hitting "customize" and dragging each widget down manually. However, it doesn't add the little progress indicator to the status bar like it's supposed to.
This (the fact that the options didn't show up by default and status bar not changing) didn't happen on another system I use. I'm not sure what the difference is. The "working" one was Windows, and this one is Mac. But I wonder if the fact that I already had items in the add-on toolbar on the Mac meant that Status-4-Evar doesn't add by default (either due to a bug or intentionally so as not to reposition the other widgets).
Otherwise, works reasonably well.
Not showing up Rated 4 out of 5 stars
I suppose I'm in the same boat as some others - doesn't seem to be working on 4.0b7 for Mac, in my case. No bar shows up, nothing seems to work at all regardless of preferences, restarting browser, disabling/reenabling, etc.
Edit: The problem was that I had to right-click and "customize" toolbars, then drag the widgets to the add-ons toolbar manually. That all seems to work, although it's not drawing the little progress indicator in the status bar like I believe it's supposed to.
I didn't have to do this on a system I installed the plugin on today. I'm not sure what the difference is. The second system is Windows instead of Mac, so perhaps that was a difference. Also on the other system I had nothing in the add-on toolbar already, whereas with the Mac I did. Maybe Status 4-Evar doesn't install the widgets in that case (either due to bug, or intentionally so that it doesn't reposition any existing widgets on the toolbar? If the latter, I think that's being way too polite (and will cause a lot of confusion like mine). It'd be safe to assume the user wants the items added to the add-on bar, and they're welcome to reposition things afterwards. Nearly every other add-on that adds to this bar is going to do exactly that.
Is the Add-ons Bar visible? It is not by default.