Rated 3 out of 5 stars

It's ok. For Firefox 4, if you do View->Toolbars->Add-on Bar it will display the status bar again and you can see the mail icon (I didn't need to do this on one machine, did on another, weird).

My biggest annoyance is that the plugin doesn't handle an already open yahoo mail tab well at all. I've lost several emails I've had open because when I clicked on the mail icon for this plugin, it reloaded the mail window losing anything I had open.

This review is for a previous version of the add-on (1.0.0.21.1-signed.1-signed).