Steven Waldman at Beliefnet has an article up called, "Deism -- It's Back!" Based on recent studies, he observes that anywhere from 3.5% to 12% of Americans are deists, not necessarily by self-definition, but because of their answers to questions about religious belief -- and that's if you use what he calls a "narrow" definition of deism.
I don't think deism ever disappeared. I would be willing to bet that the number of Americans who are effectively deists has long been much higher than advertised. There are plenty of people who identify as Christian but who don't spend much time thinking about religious beliefs, or take them all that seriously. They have a vague belief in God, but they don't feel any sort of personal connection. From what I've observed, this attitude is fairly common among Jews as well. The religion as seen more as a cultural & traditional practice than a belief system.
It may be true that deism really is on the rise, especially if you use a broad, functional definition. There's such a stigma attached to atheism, and the bonds of tradition and culture are strong. It's much easier for people to embrace a vague concept of God. Deism, even if you don't call it that, is respectable and in line with American tradition. You can attend a mainstream church, participate in all the social aspects of religion, and not have to actually believe a bunch of nonsense.