Anonymous has apparently made good on a promise to wreak havoc on the Web site of the Bay Area Rapid Transit System today, although not exactly as planned.

Earlier, the amorphous collective had threatened to take Bart.gov offline for six hours today, or twice the amount of time BART managers took cell phone service offline at some BART stations Thursday night in order to head off a planned protest then. The distributed denial of service (DDoS) attack was supposed to begin at noon pacific time, according to a release from Anonymous.

As of 30 minutes past noon, the BART site was still online but running a little slow and with one notable change to the mybart.org Web site, which currently displays the Anonymous logo as seen below.

Screen capture by Eric Mack/CNET

As screen captures of the defacement began rocketing around Twitter, news came that Anonymous hackers had also accessed and posted online a database of mybart.org with user e-mails and some addresses and phone numbers.

Shortly after the mybart.org defacement, a more elaborate mark was left on californiaavoid.org, a Web site maintained by the California Office of Traffic Safety. The #opBART Facebook page claims the defacements are part of Anonymous' protest effort against BART.

Screen capture by Eric Mack/CNET

For a brief period, BART posted two news releases on its Web site, one advising customers that its Web site could be attacked and go offline Sunday afternoon, another warning of possible interruptions to train service due to Anonymous' planned peaceful, in-person protest during Monday evening's rush hour. As of this writing, both releases are no longer visible, and BART.gov remains online almost an hour after Anonymous planned to take it down for the remainder of the afternoon.