You're looking at it backwards. The reason the S100 is so cheap is that the S110 is out. Newer models generally make the older versions cheaper. Whether the newer version is worth the premium depends.
The the lens, sensor and image processor on the S110 is essentially the same as the S100, so image quality should be about the same too. The S110 does have a couple of neat new features, though. It replaces the useless gps on the S100 with wifi which allows you to pair it with your smartphone for geo-tagging using the phone's GPS, or uploading pictures on the go. It also has a touch screen allowing for smart phone style touch-to-focus, which is actually really useful certain situations.
Whether these new features are worth the extra price depends on the buyer. Personally, I think they are. But I can see why others would argue they're not, since the S100 will give you the same picture quality for less money.
Regardless, thumbs up from me!
Thanks for the information!
I've given you reputation points for a great reply,