Amazon’s systems are very complex and on rare occasions, despite our best efforts they may experience problems. We work to minimize any disruption and to get the site back as quickly as possible.
Amazon's stock was down 4.59% for the day.
Update 5/6/08, 3:04 PM EDT: Amazon is back up.
Amazon.com is currently unavailable and shares were down almost 4% at 2:40pm EDT. It's not the first time Amazon has had trouble of this sort.
Here's a screen capture of what users see when going to the site right now: