Olympus’ E-PL1 is a camera on a mission — it not only shrinks the entry-level price tag for Micro Four Thirds cameras to $600 , it retains the same 12.3 megapixel sensor, image processor, autofocus and metering systems of its elder, the E-P1 , while introducing its own advantages that even the pricier E-P2 doesn’t offer (hello, integrated flash!). With a 720p movie mode, a 14-42mm kit lens, and access to the growing catalog...