My second, age 6, seemed excited, although not as much at son #1, and wanted to know what his brother's name is. I guess he also thinks it is a boy.
Thanks to my neighbor and best friend being pregnant (18 weeks ahead of me), little man has seen lots of Ultrasound pictures and knew right away that the picture was of a baby. He thinks the baby is in his tummy, though, not mine. I think I have him convinced that it is Mama's baby in my tummy, but he still insists he has a baby in his tummy too. He is such a mommy's boy, that he's in for a rude awakening in 6 months when mommy needs to give the new baby some attention.
Something I'm excited about: Getting into the 2nd trimester, which eases my anxiety about miscarrying, and no more nausea, finally!