I have called the Atlanta German embassy on Monday 18th.
This is my conversation with Counsler:
Me: "I'm an Indian citizen working here in US going to India on a vacation. And on my way back I'm passing thru Frankfurt"
Counsler: " What is your Visa Status?"
Me: "I'm in the process of getting my Green Card. I have a travel document to retener US again."
counsler: " Advance Parole?"
Me: "Yes"
Councler: "Yes. We recognize Advance Parole as valid visa. And you don't need to take a Transit Visa."
Me: "Is there a place from where I can print out this info."
Counsler: "It's all on the website. You can print it out from there."
One of my friends has left to India today thru Frankfurt and he is returning in a week. He too has an expired visa on his passport and an Advance Parole.
I will update you with his experience.
Please let me know if anybody has a confirmed news, otherwise.