GREEN='\[\033[32m\]' RED='\[\033[31m\]' NC='\[\033[37m\]' PS1="\u@\w \`if [ \$? = 0 ]; then echo ${GREEN}:\\\)${NC}; else echo ${RED}:\\\(${NC}; fi\`"
Interesting. However, for colorblind folks like myself, there is not enough contrast. I may play with some color combinations to see if I can use this in place of the smiley/frowny