According to Wikipedia, irony punctation have been proposed since the 16th century under the form ⸮, a reversed question mark, so the (trademarked) sarcmark is barely a new concept. However, like the more recent interrobang, this usage did not catch up and there is no standard irony mark for common latin script-based languages (irony punctuation exists in other writing systems)
On the other hand, I have seen in different contexts the following marks used for irony in a more or less standard way :
- [sic], or [sic !] (in French, I don't know if it is the use in english)
- :-) (and these emoticons being sometimes replaced by in-text graphics or plain-text characters (☺ or some newly encoded unicode 6.0 characters (pdf code chart) )
- "..." : the "unforgettable" scare quotes (and various “typograhic” 'variations' like ‘these’ and others.) This usage is to my knowledge, the only punctuation sign having escaped the written medium, with the “wonderful” air quotes.
- in a similar way, I've seen italics used for the same purpose.
About the interrobang, I have little to add to @ncoghlan answer, the excellent Shady Characters blog is publishing a an article series on it. Part 1 is already available.
Edit 1 to add : scare quotes.
Edit 2 to add : italics.
Edit 3 to add : ref. to the newly published post on the Shady Characters blog.