I think (here’s my $.02) it is a matter of user acceptance and like so many of the applications that are presented to us these days our acceptance of a icons use or function is determined by our continued use.
I personally like the hamburger (both my site and belly will atest), however that does not mean that it is a permanent fixture. If I find that user feedback indicates it should go then I’ll dump it, but this is the beauty of the medium we are working with. It’s flexible and capable of adaptation.
There are alsways going to be exceptions to the norm and alot of the examples are social sites, in essence not a great deal of top level navigation so they can get away with tabs. Others not so lucky. Consider your target, intention and content!