Unfortunately, three significant factors appear to show signs of an all-out hacker attack against Ubuntu this weekend. Update: It was a power failure, so no need to worry.
More news is here:
As for a motive, I have no idea whatsoever.
James Troup lets us know the facts
I'm afraid the cause of the outage is far more mundane – the data
centre that the Canonical servers are hosted in (including
*.ubuntu.com and ubuntuforums.org) suffered a catastrophic power
failure and as a result we were offline from approximately 12:00 UTC
to 19:30 UTC.