> Does anyone know of a source for a deeper explanation of the Deep Blue
The October 1990 issue of Scientific American had an article by two of the creators of Deep Blue, Hsu and Campbell. Of course, this was an earlier version of the machine. I would guess that they have published some more in-depth technical info on Deep Blue, possibly in the AI journals and conferences, but I am not familiar with that literature.
I wasn't able to find any detailed info on the IBM site, which is surprising. Speculating, it may be that they want to use the publicity to help sell their RS6000 computers, but in fact DB was a heavily customized version of the RS6000 and arguably got most of its "smarts" from its custom chess chips. So its success does not have much to do with the RS6000 that IBM is trying to sell, and therefore detailed technical information would not suit IBM's marketing purposes.