Over the years, Sony and Nintendo have gone from collaborators to bitter rivals. Many of Sony's moves in the video game market have been executed with the intention of breaking Nintendo. They got into the market by taking a concept that was originally intended to be a CD-Rom add on for the SNES and modding it into the original Playstation console. Much of Sony's success came from wooing away third party support from Nintendo in the mid 90s.
It was always strange to me that their relationship soured, as Sony had released several great games for the SNES including Extra Innings and Sky Blazer. Also, Sony's CD-Rom technology was being used everywhere, including by Nintendo's chief rival Sega, so one would think the partnership for this SNES CD add on would be a win for everybody involved. Money and Ego got in the way, however, and led to Sony jumping into the video game market strictly off the back of that unused tech and a desire to crush Nintendo under their heel.
a funny thing happened though, and Sony's rise in the home gaming market seemed to mirror what Nintendo had done during the 80s The NES came out of nowhere much like the Playstation did. The most popular games on Sony's systems tend to be first party exclusives, much like Nintendo, both are major players in the handheld market (though Sony is just starting to get the buzz Nintendo did with it's Game Boy line), and a growing number of gamers are fiercely loyal to one or the other. I have gone on many message boards and noticed the almost ingrained hate for Nintendo that owners of Sony's systems have and vice versa.
The quality of each company's second home console has been a tale of the same story told on different days. Much like the SNES was superior technically to the NES in every category, so was the PS2 considered a major jump over the original Playstation. With the good also comes the bad, as both the SNES and PS2 both suffered from huge amounts of shovelware that came as a result of folks figuring out that parents buy anything tied to kid's favorite movie or cartoon.
At the end of the day, a corporate rivalry led to the creation of the Playstation, and while the consoles came at different points in the game industry, their evolution seems to have mirrored each other. So the next time you hear of see a Fanboy waxing on about how great Sony is or how great Nintendo is, let them know how dependent one had to be on the other to get to this point.