Sorry about the extended downtime on the us4 node today. It's fixed now.
These issues caused the server hardware to change, which will invalidate all server keys at the moment. You'll need to re-enter an authentication key before booting your servers again. (Only applies to the us4 node)
The reason it took so long was actually because there were two separate issues. The first issue is that the physical server the node was residing on had a hardware failure, which the host of the physical server amended by moving us to a new physical server; which took about an hour and a half. The next was me finding out that the filesystem was corrupted (Which may or may not have been caused by the aforementioned problem, though it may not have been the case) causing the filesystem to be mounted in read-only mode. Fortunately it doesn't appear that it was severe, as running a disk utility to correct it seemed to be all that was needed.