Looks like iMessage is down again, as multiple users have taken to Twitter to air their complaints, mostly about not being able to receive or send messages. One user aptly referred it to as "derp mode," whatever that means.
This isn't the first time iMessage has acted up. According to Mac Rumors, the service was having issues earlier this week for several hours. Oddly enough, Apple's service page doesn't seem to indicate anything's wrong.
Why has my iMessage not been working lately?!