HipChat explains what happened with their outage on Monday. Part of it was a reconnection bug in the new Mac client:
"When a large network provider in the SF Bay Area had an issue Monday morning, it caused all of those clients to start reconnecting at once. This saturated our systems and prevented normal usage."
I could’ve done without the light-hearted mention of cat GIFs and inline face-palm image, but otherwise it’s a good post. They apologize and succinctly explain the issue. Far too many of these types of downtime reports from other companies go on and on for pages of detailed text, as if to hide the true failure in unnecessary verbosity.