The rumor was either 2 GB with 512MB reserved in dev kits, another thing was IdeaMan's inaccurate information regarding which memory was he talking about, it all seemd like it was the 512 MB of STORAGE Flash, that has nothing to do with RAM, only a portion of that gets loaded into memory.
The OS it self will not take more than 100MB, way less even if programmed well.
The only scenario where nintendo my actually reserve some additional RAM, like a 100 MB or so is the Suspend Function when games keep running and game data sits in RAM while you surf on the net and watch videos, all that flash stuff needs memory, and if games take up all the RAM with the OS then there would be no room to do practically anything while suspended.
There are several solutions to this one of which i extensively explained but I cannot link it right now cause Im typing from Wii.
Right now I recalled another solution, the FLASH STORAGE that's on WiiU may be an ideal pagefile for the web stuff, may just take a bit longer to load or seek but it wouldnt had to take RAM reservation in advance.
Still 512 MB of reservation for OS stuff and web is totally unrealistic and absurd, no way, and if for some reason it does ship like that, it will be unlocked by a system update.
And a word on BS multiplier. Stuff that is on paper totally depends on what kind of it is, ram is 3x more than X360, RAM is the biggest bottleneck, this is an important value, the real world benefit would actually be twice as much, because the difference you would see in texture quality would have been significant, not to mention better effects on top and other things possible with the extra RAM at hand.
RAM has nothing to do with performance, if the WiiU GPU or CPU is not as powerful as we previously thought that just means devs wont be able to to have that many enemies on screen or Ai operations, physics calculations etc. RAM is needed for textures, textures are the most important factor in graphics quality.
And people should stop talking about the "performance" bla bla bla, because it's anything but performance. Developers will do anything necessary in order to hit 30 or 60 FPS, all at the expense of graphics, game design, post processing, physics quality, level size and evironment, Ai interactions, ..etc. It's all about the tradeoffs, but in WiiU case the sound quality is an exception thanks to the audio DSP which makes huge sense for easier development and helps in many areas not only a better end result. Audio quality will stay the same given that it has enough RAM, it won't be directly affected and won't have to tradeoff it's performance, what's the point of utilizing 50% of Audio DSP if it can't be used for anything else. Audio DSP is such an awesome thing it also prevents developers from cheesing their GFX and tradeoffing sound making games very horrible to hear, I wouldn't be happy by the crappy sound work. The audio DSP also helps devs to not worry about sound when developing game, this leaves the sound team to fully know the capabilities of the system and can begin making their sound recordings or whatever, i belive it has a lot of development reasons that's why nintendo wont let it off, these are smarter decisions of a company that knows what it does in the software side and creates solutions in the hardware.