Nooooooooooooooooo!!! Oh wait, it's the same ^^! Don't change a working formula!

I think I understand why they're doing this.

I think that they think that the red logo is too 80's in people's minds, because they had the red logo the last time they conquered the entire universe. So the red has this retro feel that they want to get rid of. The grey logo will be for the Wii and DS generation, as opposed to a GameCube and Game Boy Advance generation with a red logo (notice both systems had game in the title). They don't want the word game in their system names or the color red in their logo. They're not about games anymore (in this marketing strategy, in my opinion, but of course they're still all about games). But now they want their logo and marketing to bring to mind a social environment I guess?

This reminds me of the Dreamcast logo's colour change in Europe, all because it's far too similar to that of an existing company.

Yep. Nintendo's trying hard this gen to establish a corporate identity the new market can recognize. The old red logo, the purple Gamecube, and words like "game" and "boy" all give off the impression that they're toys made for children. The new Nintendo is trying to draw in people from all ages. The same people who thought video games were only for kids. A big part of that is creating consistent and professional looking designs for their products and logos. It's all about image.

I could go on a whole rant, but I'll leave it at that.

I love gray.

I like the gray, but I think they should have kept the red and used it to refer to "classic" Nintendo, before the Wii. Sorta like how they stopped using Gameboy once the DS hit.

Well hell, why not? Most Nintendo products these days feature a neutrally colored Nintendo logo on them somewhere as it is. The logo itself remains unchanged, after all. It may be that this was what they had in mind all along, actually. Maybe they didn't go with gray back in the NES days was that it would make the logo totally unreadable on the starkly gray NES. :P