The problem with 2257 for webmasters is that IF the feds want to throw the switch on prosecutions they could very easily. A bot could easily see who does and who doesnt have proper notices on their sites. Even if you have the docs but do not have the notice requirement correct, its a felony.
The feds are also using 2257 as an add on for obscenity prosecutions and as Kevin pointed out for CAN-SPAM Act violations. They have conducted, I think, 27 inspections and so far only several companies have not had violations.
As for civil side of not having 2257 correct, it opens up a potential to be sued by a competitor for unfair business practice claims -- see the Vivid v. Pornotube litigation.
And remember they just issued new regs. Regs that will be harder to overturn on Constitutional grounds. Perhaps the Feds are ignoring 2257 or they are waiting to make sure that they got it right this time. Either way I dont see 2257 going away, but then again I dont see mass criminal prosecutions as well.
Its a law, like any other. If you chose to comply you are in a much better position then if you dont. It really comes down to how risk adverse a webmaster/owner/blogger ect is.
www.2257Safe.com gives the industry an inexpensive solution to this problem. If people choose not to protect themselves I dont think fear is going to motivate them. Either they like risk or they do not.