Ok, I checked a friend's E-Ballast today, and it appears that polarity does NOT matter with E-Ballasts. He's using the ARO brand, and both wires coming out of the ballast going to the mogul are the same color, so that tells me that it doesn't matter which wire is wired to the black wire of the mogul.
I'm still going to wire my mogul with the black wire to the tab since I don't know if this holds true for all ballasts. Who knows, one day I may want to switch ballasts, and I don't want to have to remember to check if the mogul is wired correctly.