I heard about that engine over the summer on Autoline After Hours (
AAH #63) They had Hofbauer come in and talk about it. Its pretty neat and there are a wide range of potential applications for it. The show is about an hour long, maybe a bit longer but you can probably skip the first ~20 minutes as they'll be discussing 6 month old automotive news.
Oh, another little factoid: Bob Lutz is on the board of EcoMotors (the company that is developing this engine)