Great extension, solved my problem of configuring meta tags for category blog layouts.
Thought it might be useful to provide a slightly more detailed installation guide... hopefully someone will find it useful.
1) Download the Tag Meta zip file, you will need to unzip this first to install the TWO included extensions (com_tagmeta_1.1.zip and plg_tagmeta_1.1.zip). As you have probably guessed one is a component and the other is a plugin. You need to install both separately.
2) You can check both are installed properly by navigating to 'Extensions' > 'Install/Uninstall'. Tag Meta should be present in both the components and plugins sections of the Extension Manager.
3) You now need to enable and configure the Tag Meta plugin... 'Extensions' > 'Plugin Manager'. Select 'System - Tag Meta', change 'Enabled' to Yes and configure the parameters.
4) To start using Meta Tag navigate to 'Components' > 'Meta Tag' where you can create new items. These are based on the page URI, when a matching page is found the title and meta details are automatically overridden.
5) More usage information available in 'Components' > 'Meta Tag' > 'Abou't.
Note: There is no need change any Menu Item type to Meta Tag.