I'm not sure why people are up in arms about this? I've had the same problem for a few days to varying degrees, but it doesn't affect at all my ability to play--- any mods you've already downloaded are stored locally. The only real problem is checking on updates through the NMM. I've added mods without issue, though manually.
I'm sure they are working on it, and haven't commented because they already did, really with that big letter from Dark0ne.
Actually it's not just that, it also is stopping any files from being downloaded via NMM because it says they don't exist.
I'm fine with waiting though, I just hope it gets fixed sometime today.