According to Sony, the HDR-TG1 is not much larger than a cell phone. That is certainly a small piece of hardware to pack in the ability to capture 1920x1080 video with 5.1-channel surround sound.
The HDR-TG1 has a 2.7-inch LCD display, face recognition technology, auto-focus and color control, and a 4.0-megapixel still capture capability.
The camcorder also has an automatic Zoom microphone that focuses sound capture on specific people or objects that the camera is focused on. And everything is captured in 5.1-channel digital surround sound.