DVD is available
http://www.defafilmlibrary.com/product_info.php?products_id=99&osCsid=cdc4111a26df999ccec3b57c50360e94
http://sachlichkeit.net -> Film blog
It's also available in Germany:
http://www.amazon.de/Kuhle-Wampe-oder-geh%C3%B6rt-Welt/dp/3898488764/ref=sr_1_1?ie=UTF8&s=dvd&qid=1241886580&sr=8-1
No English subs, though.