First off, I want to say that the Canon S400 is a great camera. I have one are like it a lot. The image quality of the S400 is on par with the Contax. At ISO 100, I'd say that the Contax has a little less image noise because of RTUNE. But from ISO 200 on, it's a horse race.
The S400 has a better macro mode. You can frame things much tighter than with the Contax. When I have to grab a quick closeup, I usually grab the Canon.
But the Contax is a better street shooter because you draw less attention with it by holding it at waist level or any other angle for that matter. Its movie mode and burst modes are better than any point and shoot I've ever tested.
The Contax also has those shooting modes you inquired about -- Sports, Portrait, Night View, Night Portrait, Macro, and Landscape. The S400 doesn't have Sports and Portrait, but it does have the others. It just spreads them throughout various menus while the Contax lists them all under the Scene menu.
The Contax has a manual focus mode that allows you to choose from 5 positions on a scale.It also has Spot and Wide Spot auto focusing. I use Wide Spot most of the time.
The one thing I find myself using a lot lately is the in-camera editing function that allows me to crop and sample down images. It saves a copy of the image (your original hires is safe) to a different directory on the SD card. I then put the SD card in my Palm T2, navigate to the resampled directory (appropriately called RESIZE), and copy the images I like to the Palm's internal memory. I can do this while waiting for my dinner and never have to touch the computer. Because the resampled images are only 320 x 240, that take hardly any memory on my Palm.
I can also use the Palm to send any of the images off the SD card -- hires or low -- via Bluetooth to another device. I'm currently working on an article that covers all of this stuff. I should have it ready to go the first week of April...
It's all quite fun :)