I'm hoping it's stored in NVRAM permanently, but I have no idea as I have not tested for more than a few minutes and have gotten no official response.

Just to close the loop here, I'll answer my own question. According to tp-link support, yes, the HS100 will return to the previous ON/OFF state after a power outage. I bought and tested a HS100 and...

Model : Hardware Version : Firmware Version : ISP : Anybody know if there will be an IFTTT Service developed for the HS100 Smart Plug?? reference: https://ifttt.com/discover

Model : Hardware Version : Firmware Version : ISP : I plan on using the Smart Plug to power something that will normally be on, and it is imperative that it remain on when power returns after a power...