!
I've spotted a tendency in new media for people to over use the exclamation mark. I'm very guilty of it - in fact it's been known to spill over into papers and "real" writing!
I've seen it in many other blogs (Mrs Lev among others), e-mails and texts. Maybe it doesn't matter - its part of the new lexicon - or maybe we're just getting lazy with words and relying too much on !!! for emphasis.