This topic has gotten a little strewn about (mostly my fault I think), but, since I feel comfortable with what I have working, and seen it work on a 25, 45, and 85, I started looking into the temp sensor support. Post #1186 here: https://budgetlightforum.com/t/-/25032 (STAR firmware thread) has the latest.
Found the Atmel doc http://www.atmel.com/Images/doc8108.pdf, and one fairly good ref for sample code http://andrey.mikhalchuk.com/2011/06/20/reading-attiny854525-internal-temperature-sensor.html.
This is a variant implemented for the 84: https://harizanov.com/2012/07/using-attiny-84s-internal-temperature-sensor/. It has a link to a github repository for the source code.
This one has a plot showing readings, bit for another Atmel AVR MCU, guess it's at room temp: http://www.narkidae.com/research/atmega-core-temperature-sensor/