This may not seem like a big deal, but it is a serious threat to online speech.

On WIRED, Xeni Jardin has an article concerning changes to a little-known anti-child porn rule codified at 18 USC 2257 (Porn Law Draws Adult Sites' Ire):

Under Title 18, Section 2257 of the U.S. Code created under the Child Protection and Obscenity Enforcement Act of 1988, producers of adult magazines and movies must make identification documents available to federal inspectors on demand.

But the suggested changes would bring an extensive array of new responsibilities to webmasters. While the current law applies to "primary producers" -- photographers, filmmakers and others who actually create adult material -- the new changes would affect "secondary producers," such as websites, that distribute content created by other companies. The result could have far-reaching consequences for the entire adult industry, but it would have a particularly harsh impact on online companies. [link in original]

The record-keeping regulations may not seem strict, but considering the quicksilver nature of the pornography business, can actually be quite onerous and do little to protect the children they are ostensibly aimed at. As one anonymous commentator notes, this law basically makes it easy to shut down online porn companies (or even porn bloggers) they don't like:

"Unlike enforcement of obscenity laws, which require vetting of community standards, this is 'yes or no, do you have the documents?' for webmasters," said one technology provider close to the matter who requested anonymity. "This is a much more efficient way to wipe out online porn, a goal Ashcroft has already stated."

18 USC 2257 is a real danger to publication on the Internet. This little known aspect of the federal anti-child pornography laws (which include 18 USC 2251-60), requires those who produce visual depictions of actual sexually explicit conduct to maintain records about the identities and ages of the performers. Those who don't are subject to 2 years in jail for a first offense. This law never made any sense, but its burdens on speech were relatively minor when pornography was generally produced for profit. Now that amateur pornography is readily distributed via the Internet, these record-keeping requirements substantially burden constitutionally-protected speech. This is a statute whose enforcement should be carefully watched. [link, italics in original]

Bonus: As I mentioned before, "I believe there is a reasonable argument as to why 18 USC 2257 violates the copyright clause. Any guesses as to why I might think that?"

UPDATE 2030 PT
Thoughtful comments on this issue from Christian Libertarian fallinggrace.com (DoJ Proposes Unethically Attacking Porn Through Ambiguous Regulations).