Rumour has it that an egg embedded in JK II will be a special one:
Max the pshyco bunny is probably going to make his appearance again. But this time he'll be armed and dangerous. Watch out, 'cuz he's possibly either going to have a lightsaber or a concussion rifle.
Also look around dark corners and into the sky on level one. George Lucas' face makes an apearance quite a few times.