Update (6 p.m. EST): @YourAnonNews sent out a tweet taking more explicit credit for downing CIA.gov (which is still unresponsive).

Original: The Central Intelligence Agency's website CIA.gov is unresponsive in what looks a lot like a denial of service attack, but it's a bit too early to blame it on Anonymous, which usually likes to loudly take credit for these kinds of things. Of the key Twitter accounts that usually tout successful hacks by the loose-knit hacking network, none directly took credit for the website take-down. Youranonnews, which is the closest thing the group has to an official account, tweeted the news, but cited Russia Today's story about the attack. It didn't claim credit. Another reliable Anonymous news feed, AnonymousIRC, hasn't mentioned the CIA.gov attack. Only the account @AnonymousPress, which Russia Today cited, appeared to take credit, and that wasn't very explicit: "http://cia.gov DOWN | #UMAD? | #Anonymous." 

But if it is the work of Anonymous or some allied hacker, it wouldn't be the first time they've targeted the CIA. Back in June, the Anonymous splinter group LulzSec took credit for bringing down the site, "for the lulz." If this is a repeat of that, they're being a lot quieter about it, which isn't Anonymous's normal M.O. on what it's dubbed FuckFBIFriday. One well-known Anonymous hacker, who goes by the handle Sabu, reportedly led LulzSec over the spring and summer and still tends to broadcast Anonymous's claimed victories. His account mentions nothing so far of the CIA hack.