Believe me when I tell you that the legal issues surrounding this have nothing to do with a constitutional right to privacy. And, in fact, state law and state courts are going to be the primary battlefields on which such issues are fought -- unless Congress, using its power under the Interstate Commerce Clause and Copyright Clause choose to occupy the field by enacting a statute that preempts state laws. But absent that, claims will be primarily governed by state law, such as contract law (e.g., does the End User License Agreement constitute a binding contract?) and state consumer protection laws (e.g., are the disclosures in the EULA so vague and opaque as to be misleading or worse?).

Ironically, you may scoff at state law, but in many ways the states have more latitude than and are more pro-consumer activist than Federal courts can be -- in fact, sometimes too much so IMHO (you've heard of "junk science"?). For example, most of the "pro consumer" class actions you hear about, involving claims for defective products (asbestos, cars, drugs, etc.), involve state laws.