I've never had a problem finding a gig even though I'm a felon, but I don't work with BigCorp because that's not my scene (and it's probably harder to market myself as a felon to anyway):
At the end of the initial phone call / screening, I tell them, transparently: "there's no way I can pass a background check by the way"
It has always been well received, even to recruiters and head hunters.