I made my first pair of socks out of worsted weight acrylic. Red Heart--not the nice stuff! They're pretty cushy and with repeated washing/drying they've turned out perfectly soft and comfy. They're good house sock, very warm--but yes, if I wore them with shoes they'd be sweaty (ick!)
I think nice baby soft acrylic would be perfectly fine and comfy for baby socks.
[highjack]Jen I made Bambozelle for my mom last month, it's really cute and fun! Enjoy! [/highjack]