How to turn off notifications from Facebook Messenger on Android Gingerbread?
If you have root access on your device, an application like this may work for you. I cannot test it as I have no Gingerbread devices. 



This option only lets you turn off notifications for 24 hours (what a terrible feature)

Open the messenger application.

Go to the 'cog' icon for settings. 

Turn notifications off. 

This image shows the Icon, and shows the 'Notifications' option, but the arrow isn't pointing to it!