WordPress.com saw DOS attacks beginning Saturday, and the attacks were continuing till yesterday as some of the users still could not log on to their site.
Matt Mullenweg, the brains behind WordPress and its spokesman, also confirmed these attacks. There were spikes of about 6 GB of incoming traffic rendering the blogs inaccessible by some users for almost up to 15 minutes.
Although the service has been restored, the company is still working on returning the performance to regular levels.
A DoS attack is an attempt to make a Web site or service unavailable to intended users by flooding the service or site with incoming data requests, such as e-mails. Motives for DoS attacks vary, but perpetrators mostly target companies with high-profile, highly trafficked Web sites.
More more information on Global Denial Of Service, check out ATLAS for the day to day summary.
Shadow Server community is also reporting about these attacks along with the attacks on casino websites.