The two components communicate wirelessly. There were several options I considered for this link.

# Ethernet on the controller, wifi on the receiver

* Pros: good library code available, entire stack on the chip, high level protocol (http?)

* Cons: expensive, hard for the end user to set up

# XBees

* Pros: reliable, lots of library code, stack

* Cons: moderately expensive, no hardware UART on the ATTiny85

# Nordic Semi NRF24L01

* Pros: inexpensive ($3/pair), compact, respectable range - even indoors

* Cons: not a lot of library code out there, lower level protocol.

In the end, I decided to go for the NRF24L01 and purchased some sample units to use in this process.