Know Thy Enemy
I can just picture the director thinking, "Damn. I'm going to have to distract the audience from the fact that hiding the moonstone in a soap dish instead of - idunno - a locked safe was pretty dumb. (Or maybe a vervain-filled well or a box in the attic or possibily the freezer or just plain giving it to someone who doesn't live in the same house as Katherine...) I know! I'll have Ian Somerhalder take off his shirt."
Which is not to say the shirtless didn't work. It worked. Totally worked.
But while I did love Nina Dobrev's "duh" glare as Katherine figured out where the moonstone was, I'm so hoping Paul Wesley's little smile at the end was Stefan's way of reassuring me that he moved the silly thing and replaced it with a duplicate and didn't tell because he's just that much smarter than his brother.
And if he didn't... well, I'm sure he'll also be taking his shirt off eventually and it turns out that yes, I really am that shallow.