An example eventcmd script for posting pianobar events to Last.fm with Scrobbular.

eventcmd

#!/bin/bash

# create variables
while read L; do
    k="`echo "$L" | cut -d '=' -f 1`"
    v="`echo "$L" | cut -d '=' -f 2`"
    export "$k=$v"
done < <(grep -e '^\(title\|artist\|album\|stationName\|pRet\|pRetStr\|wRet\|wRetStr\|songDuration\|songPlayed\|rating\)=' /dev/stdin) # don't overwrite $1...

username='<YOUR GOOGLE USERNAME>';
secret='<YOUR SCROBBULAR SECRET>';

case "$1" in
    songfinish)
        # scrobble if 75% of the song has been played but only if the song hasn't been banned
        if [ -n "$songDuration" ] &&
                [ $(echo "scale=4; ($songPlayed/$songDuration*100)>50" | bc) -eq 1 ] &&
                [ "$rating" -ne 2 ]; then
            curl -X POST --data-urlencode "username=$username" \
                --data-urlencode "s=$secret" \
                --data-urlencode "track=$title" \
                --data-urlencode "artist=$artist" \
                --data-urlencode "duration=$((songDuration/1000))" \
                --data-urlencode "album=$album" \
                http://scrobbular.appspot.com/scrobble
        fi; 
        ;;  

    songstart)
        curl -X POST --data-urlencode "username=$username" \
            --data-urlencode "s=$secret" \
            --data-urlencode "track=$title" \
            --data-urlencode "artist=$artist" \
            --data-urlencode "album=$album" \
            http://scrobbular.appspot.com/now_playing
        ;;  
esac

You also need to chmod +x the eventcmd file and add the following to your ~/.config/pianobar/config file:

event_command = /Users/rleland/.config/pianobar/eventcmd