It seems that minecraft.net, Minecraft’s authentication service, and multiplayer sessions service are all down (source). You can check in here and we will post when these services are back up.
UPDATE: Everything is back up! Get playing 😉
Minecraft is down (6/10/14)
CategoriesMinecraft
Thank you for informing me this matter.
You’re welcome. Does anyone know the cause (I heard something about Mojang taking down servers). It might also be DDoS, as indicated by the source and minecraft.net…
the .net site just went down too maybe its a good thing and its about to be fixed
Yep, everything is back up.
https://help.mojang.com
heres a better link with server status