From what I can tell, most--if not all--have been sent. I believe they send out 20-25 invites and have a waiting list of a similar size. I received a follow up email the next day with specifics, and I imagine others did as well.
ALSO: anyone else who is going, feel free to PM me!
In early January, one person posted about email invitations for interviews with both UC Boulder and UT Austin. I've seen nothing else since. Does anyone have any information about these two programs?
EDIT: Also, has anyone heard from Duke?