Update 12:13pm EST - Twitter.com is finally up for many users, DoS attack still ongoing. Facebook and LiveJournal also experiencing issues.
Update: 11:26am EST - Twitter says site is back up but they're still defending against the DoS attack. I personally can't access Twitter.com, can you? Leave a comment.
Twitter went down this morning and it's not the usual fail whale situation. Instead, Twitter issued a statement on status.Twitter.com that they're defending against a Denial of Service (DoS) Attack.
A DoS attack is a malicious attempt to bring down a website or application so that its users cannot access the service.
Twitter went down around 10am EST.
Stay tuned to Search Engine Watch as this story unfolds.