Here's some very interesting, seemingly new information about the console war in the 90's:
http://www.mcvuk.com/news/read/tale-of-two-e3s-xbox-vs-sony-vs-sega/0118482
About halfway through the article ex-Sega boss Tom Kalinske starts talking about working with Sony in the early 90's. It is pretty much common knowledge by now that the Playstation started out as a CD addon for the Super Nintendo, but Nintendo cancelled the deal and instead entered a partnership with Philips behind Sony's back. What I've never heard before however is how Sony approached Sega right after that, things were proceeding just fine and dandy until Sega's Japanese division heard what was going on and put a stop to it.
Seems like it always ended up being Sega of Japan that made all the terrible decisions that ultimately forced Sega out of the hardware business. They were immensely successful in America and Europe, but never really got a strong foothold in the Japanese market and it almost feels like they were intentionally sabotaging their western divisions out of spite or something.