I've been spending some more time on piano lately and am working my way slowly through the piano for non-pianist section at the end of David Berkman's book on Jazz Harmony.  It's been amazingly helpful.  Unlike most piano for non-pianist resources I have seen, it takes a very practical approach and focuses on the most important things the non-pianist needs for purposes of working on harmony, arranging, etc..   It helps get you up and going quickly without getting too bogged down.