perhaps you can try the python script found here. It uses the google translate API.

Edit: seems that that api is a paid service now. Maybe you can use the oneliner from commandlinefu

 translate(){ wget -qO- "http://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q=$1&langpair=$2|${3:-en}" | sed 's/.*"translatedText":"([^"]*)".*}/1

/'; }

Edit 2: try using libtranslate-bin available from the repositories

example usage:

 echo "hello" | translate-bin -f en -l

and to use google translate:

 echo "what are you doing" | translate-bin -s google -f en -t fr

and to convert kanji to romaji

echo "what are you doing" | translate-bin -s google -f en -t ja | iconv -f utf8 -t eucjp | kakasi -i euc -w | kakasi -i euc -Ha -Ka -Ja -Ea -ka