Meanwhile, what's so vague about "Another World is Possible"? It certainly says no less about what we want than "Workers of the World Unite." Unite for what? Nobody doubts what other kind of world is being called for. They just don't believe it's possible.
Finally, I'm personally sick of the idea that general calls for allies are somehow vague. Socialists can come from any class background. I agree that it is vital to respect, include, and intellectually privilege the working class, but the left has a problem with dunderheaded purity in this area. Besides, everybody is a worker, after all, by definition.