Invites are back up, I sent you one, hopefully it will work. Let me know.
Edit: Robin still didn't get her invite email, it's taking longer than when I got mine. Keep your fingers crossed.
Edit2: If anyone has gotten an invite previously that stated Google was over capacity, TRY AGAIN, using that same email. I got Robin in by clicking on "Learn more about Google+". From there it went straight to the join screen. Good luck guys.
BTW - I would like to thank the members of Reddit who have kept me informed about the goings on re: Google+. I got my initial account from a Redditor, and tonight they let me know that invites were open again. Upboat for you all. Heh.