I have installed Ubuntu 12.04, with Empathy 3.4. I discovered that ability of linking contacts from different networks is missing from context menu. Is it bug or I need to install something?
I figured out the problem: The gnome-contacts package needs to be installed.
And linking works differently. When you select "Information" in the context menu, Gnome Contacts is opened, where you can link contacts with the same name, which then creates a metacontact in Empathy.