I was able to upgrade my Peanut firmware using R072. As discussed here, I first needed to remove and re-add to get it to show up as a Peanut Plug. The upgrade still failed after I unplugged and plugged the peanut back in. It may have been a coincidence, but after rebooting the A+, the upgrade was successful. The Peanut seems to be working fine (I was having reliability issues with it before) and power readings look accurate, although the A+ is still saying there is an upgrade available for it. Just for grins, I tried updating again, but this time it is failing every time. I had the Peanut about 4 feet from the A+ through all of this.