The Canon Powershot S100 is available right now. I agree it is an extremely interesting camera.
Release dates are not easy to find because they vary by region. Typically, there
will be a press release announcing the intended date approximately, usually something like End Of November. At that point stores will usually begin to get the model, starting with the bigger stores in major population centers. You can often find press release summaries at camera and gadgets sites but your best source is the manufacturer's News page. If you are outside of North America, you should look for regional publications. Sometimes a model will not be at all available locally.
This year has been particularly unlucky because the Japan earthquake and tsunami, followed by floods in Thailand have delayed by several months quite a few cameras announced since the last quarter of 2010.