Not sure if this has been posted here before, but this is an interesting development from the increase in web-based, and thus somewhat impersonal, communication over the last few years.
http://www.upi.com/Odd_News/2010/01/12/Company-creates-sarcasm-punctuation/UPI-55751263324278/?usesarctags
I have frequented a lot of forums in my day and this is the only one that uses teal to denote sarcasam.
Most places people are either use the sticky-out tongue to denote sarcasm :P or just put the phrase inside of <saracasm></sarcasm> tags.
/onTopic - That punctuation looks like some weird squiggly tit.