She's been working at it for a few weeks now, little gurgly not-quite-giggles. Tonight, she really let it go and it sounded like a true laugh - squealy happy happy joy joy out of her almost 3 month old little body.
Her Papa was doing the Grover. You know, "Neeeeaaarrrrrr! Faaaaaaaar!" with her into a mirror. And she giggled, sweet little baby giggles!
I just about cried.