This is a serious question, because I want to get a Powershot and have been looking at them. Why are there so many models? The SD4000 and the S95 seem very similar. Several families - S, SD, SX, A, - overlaping price points, very similar features.
Has anyone sorted this all out?
A series: "Easy and Fun" budget cameras ranging from point-and-shoot to prosumer cameras
D series: waterproof, freeze- and shock-resistant
E series: design-oriented budget cameras
G series: flagship cameras with advanced features
S/SD series (also known as PowerShot Digital ELPH, Digital IXUS and IXY Digital): "Performance and Style" ultracompact point-and-shoot cameras
S/SX series: ultra-zoom cameras
S series: originally a series of compact point-and-shoot cameras, currently a series of prosumer cameras slotting beneath the G series
Not sure that helps, though.
Specifically, for the SD4000 vs. S95, see THIS
. Basically, the S95 and forthcoming G12 are the logical choices from someone used to shooting with a dSLR - RAW capability, good manual controls, etc.