LIKE almost every other American architect who came to prominence in the recent gilded age, Michael Maltzan built his reputation with commissions for prestigious museums and luxurious private houses. In 2002 he garnered national attention for his graceful design for the temporary Museum of Modern Art in Queens. His most recent projects include a flying-saucer-like house for the artists Lari Pittman and Roy Dowell in the foothills of the San Gabriel Mountains and a far grander, 28,000-square-foot Beverly Hills mansion — part art gallery, part home — for the investor and former Hollywood über-agent Michael Ovitz.