Like its 10x-zoom sibling, the SX120 IS, the SX20 IS doesn't change much from the previous version, the SX10 IS. The key differences are a bump in resolution from 10 megapixels to 12 and 720p HD-quality movie support as well as HDMI output for easy connection to an HDTV. It'll be available in August for $399.99.
The SX20 IS keeps the previous generation's 20x f2.8-5.7 28-560mm-equivalent lens. Optically stabilized, of course. Another bonus: the zoom works while recording movies and it uses a new motor designed to be quieter so it's not heard in the audio when you zoom.