For someone who understands this stuff better than me, is it safe to assume these DC fast chargers aren't compatible with Model S?
It doesn't say but I would almost guarantee that is a CHAdeMO charger. The Model S currently does not support CHAdeMO however Tesla has said that they were going to provide CHAdeMO support in Japan (where it is ubiquitous) so there is a chance that we will get it here eventually.
I think they are compatible. Here's the website of the charger:
The press release mentions one DC fast charger and one Level 2 charger at each station. The DC is almost certainly not compatible with the S, but the Level 2 should be.
The fast DC chargers at Cracker Barrel are all CHAdeMO. As @PaceyWhitter mentions, there are rumors of an adapter for the Model S (it will be very important in Japan and Europe, where there are more CHAdeMO chargers), but it isn't available yet and no guarantees it will be. If it were, you could expect charging about half as fast as a Supercharger.
Do not forget, there is a lot to CHAdeMO so that adapter will not be cheap.
CHAdeMO is a kludge compared to the TM connector. It has 8 (EIGHT!) data lines which have to be fed. Quite a trick from the Tesla 2-line rig. (Proximity and pilot, only one needed at a time, depending on source.)