I don’t know if the whole of WordPress.com was down, but this blog certainly was, and so was the main page of the site. It lasted for about 20 minutes, I think. We seem to be back now.
Update: Matt not only commented here right after the outage, but also posted to the WordPress.com blog, describing and explaining the outage, and describing the impressive and growing hardware powering WordPress.com.
Changing Way 
Yes there was an outage, blog post about it coming soon. Sorry for the inconvenience.
Matt,
Thanks for stopping by. The outage didn’t last long and, by the time I got to the wp.com forum, there was a post explaining it.