The Arduino Uno is based on the Atmel ATmega328 processor, which is the smallest ATmega processor that uLisp supports. It runs at 16 MHz and provides 32 Kbytes of program memory, 2 Kbytes of RAM, and 2 Kbytes of EEPROM. Other boards based on the ATmega328, such as the Arduino Nano, should be equivalent.
It gives room for about 310 cells, and it's capable of running all the Simple examples, using short symbol names.
I've tested uLisp with an official Arduino Uno board:
Also with a Makerduino UNO from MakerStudio:
The Arduino Uno has an orange LED connected to the digital pin 13 which you can flash with the following program:
(defun b (&optional x) (pinmode 13 :output) (digitalwrite 13 x) (delay 1000) (b (not x)))
Run it by typing: