Keep in mind - 99% of the population wouldn't have been able to figure out how to spoof the user-agent to get into the AT&T site, and most of those that could, wouldn't have gone beyond extracting a couple IDs, and then notifying AT&T.
Weev's sin (if not felony behavior) was extracting 100,000+ personal email addresses, and the exposing them for the sheer purpose of embarrassing people he despised. Do I believe he engaged in illegal behavior? Yes. Do I believe it merits years in Jail? No.
With regards to legal obligations - In California, the closest I can find is Bus. & Prof. Code §§ 22575-22578 [1]. It is a requirement for site collecting personal information to "conspicuously post its privacy policy on its Web site"
I can't find any laws in California that require the securing of this information beyond that, though.
[1] http://www.leginfo.ca.gov/cgi-bin/displaycode?section=bpc...
It's not the world's greatest hack, but it certainly was using the system in a manner that I'm certain AT&T did not intend. The IRC logs indicated that they knew what they were doing was likely criminal, and if AT&T discovered them, would "sue" them.
Whereas I'm guessing PG would be fine with you incrementing the number on the HN URL. And I'm pretty certain that's not criminal behavior.
It's important to note, that just because weev was hacking the AT&T site, didn't mean it was a criminal hack. In my mind it barely crosses the line - and he gets punished somewhat, but I'm thinking a week in jail and 30 days community service - not the silly levels that the feds are going to in this case.