New version available Rated 5 out of 5 stars

Download 2.8 here, works perfect:
downloads.mozdev.org/webmailnotifier/wmn2.8.xpi

This review is for a previous version of the add-on (2.7.10). 

Rated 5 out of 5 stars

Works really good with Gmail, and is space saving in status bar, compared to say Gmail Manager. Plus supports a lot of servers.

This review is for a previous version of the add-on (2.6.5).