Thanks Wes for this one.
AOL Instant Messenger announced a service sending instant messages to cell phones via SMS. I signed up for the service and enjoyed it for a few days, however I just came across this gaping bug in it: My friend sent me a message right before she got offline. AIM to her responded with the auto-response saying that the message was forwarded to my cell phone. That response went to her cell phone, since she got offline after sending me the message. Naturally, AIM responded to my cell phone saying that my auto-response was forwarded to her phone...which made AIM respond back to her phone saying her auto-response was forward to my phone. Pretty much an infinite loop...

Read the complete story over @ NeoWin.