Written sarcasm

I like the use of brackets around an exclamation mark to indicate written sarcasm, such as "Oh, yes, it all makes sense now(!)". I saw it first in Stargate SG-1 subtitles. It does require establishing it as a convention before people recognise it intuitively, but it's well known that written English could use a sarcasm-mark. Whether it's this or something else doesn't bother me. I'm surprised it hasn't happened yet.

Mokalus of Borg

PS - Some people prefer as the marker.
PPS - It takes longer that way, but it is clearer for the uninitiated.