Well fanboyism and offensive behavior has always been around. It is at new heights though. The last time the problem was even close to this large was during the N64 and PSone generation.
The Sony fans are incredibly bitter and vicious because they just went from being in the lead 2 generations to being in the very back by a large difference. The same thing happened with the N64. The Nintendo fans became really vicious and everyone became divided into factions. During the PS2 era this subsided. People got used to the situation and after the first 6 months of the generation relative acceptance formed.
This generation, there are the bitter losers and the boasting victors. The problem isn't that Nintendo fanboys (minus a select few) are attacking Sony, it's that they are taking every moment they can find to gloat and boast their success, which they do quite often due to 2 generations of bad sales. This prompts the bitter losing faction (sony fanboys) to take offense to the boasting, which they see as insults, and lash out at Nintendo.
This is compounded by many former PS2 owners feeling shafted by Sony's new direction. You said Sony fans have always cared about graphics, but I sure didn't. That's why I bought a PSone and a PS2, the weakest systems of their respective generations by far.
Not only that, but the PS3 is severely lacking in one of the most important genres of the PS2 and PSone: JRPGs, and filled with a genre that many Sony fans showed disdain for in the past: shooters. It's also been much slower to introduce the most popular games on the PS2. The PS2 had FFX, GTAIII, and GT all in it's first year, and the PS3 has none of those. FFXIII won't hit outside of Japan until 2009. GTAIV has gone multiplatform and still won't hit until 2008. GT won't hit until mid-2008. Of course, some people simply feel shafted by price. Either way, you will find much more hate from the former fans than from the people who always preferred Nintendo or Microsoft. Ever heard the phrase, there is nothing more dangerous than a lovers scorn? Same basic deal.
Microsoft's position is really wherever the fans happen to fall. Some are Wii60, some hate the Wii because of the Wii not having good graphics. They end up being a 3rd wheel in a much more established rivalry, but of course it just increases the friction.
All of this builds up to a gigantic mess of hatred that you aren't going to be able to control by simply bitching about it on a forum post. As the generation progresses and becomes more set in stone it will cool down some, but right now, grab your flame shield and stand back.
