Despite a 3x zoom probably being the best for keeping photo quality intact, it looks like a 5x optical zoom will be supplanting it as the point-and-shoot norm. Nikon's doing its part to help that along with the 12-megapixel Coolpix S640 and S570.
Both cameras measure 0.8 inch thick and feature a 5x f2.7-6.6 28-140mm-equivalent lens on front and a 2.7-inch LCD on back (though the S640 has an "antifouling and water-repellent layer"). Where the S640 pulls away from the S570 is in performance.
Nikon's claiming a start-up time of 0.7 second as well as shorter autofocus and shutter lag times. This would be great for Nikon since typically its cameras are average performers.
The S640 also gets you optical image stabilization (the S570 is electronic only), subject tracking, and sensor sensitivity up to ISO 6,400 at full resolution (not that you'd want a 16x20-inch print of something shot at that ISO).
The Coolpix S640 and S570 are out in September for $249.95 and $199.95, respectively. The S640 comes in colors with evocative names--calm black, velour red, precious pink, and pearl white--while the colors of the S570 are more economical: black, red, blue, and pink.