[Agrajag]

<3 is indeed supposed to be a heart.
In fact, the first time I saw it, many years ago, I thought it was an *** (the kind that is usually used before "hole") wearing a hat, and thus I called it "asshat". Not long after that, "asshat" became a popular insult. (and since then it's popularity has faded.)
Not that I'm implying there's any causality involved.