This'll be a noble spoiler, then - as Joffrey is regarded as worse than the Mad King by Tyrion Lannister, and you need something nice to look forward to, as a lot more bad shit will happen.
Good news: he does die in "A Storm of Swords", but it may/may not be within this season, as they split the damn book. I can see it as a season-ender, to make a cliffhanger for the 2nd book.
Spoiler that probably won't happen in the book, as they've accelerated Sansa's storyline: Sansa is forced into marriage with Tyrion Lannister LOL!