Well, if you havent figured it out by now, at about 11:30pm CST last night, a huge DDOS attack was started by a worm that is attacking MS-SQL servers via the MS-SQL monitor service on port 1434. If you want to see how vulnerable the net really is, you are looking at it. At one point almost half of the root namesservers were down with most of them suffering major packet loss. The worm looks like it is targeting the DDOS attack at these nameservers and the the major internet backbones. This is why you will notice the slowdown visiting many sites.
Here is an interesting graphic that shows you exactly when the attack started:
Heres hoping people with MS-SQL servers will get there butts in gear and patch the hole that this worm has been exploiting. The fix has been available for six months. Not that this is the sysadmins fault completely, but when dealing with Microsoft products, you should know better.