I just went to call someone and my phone had a nice "Check SIM" error message on it. So, I yank the battery and remove and reseat the SIM. Make my call and everything seems fine. Then a minute or so later I get some kind of "Message sent" notification I've never seen before. Sure enough, the phone had just finished sending an SMS out to a bunch of people that I'd written like 6 hours ago.
Fucking wonderful...
Anyway, sorry to those unlucky enough to be on the receiving end of that...