My PS3 is a 60 GB european launch model. From time to time it makes some noise, nothing annoying though.

Last week it was my brother's birthday and i bought him a PS3 slim. I have noticed that the slim is even quieter. Which has made me kinda jealous lol

Originally (for me) it was X360 > PS3 > Wii, however my Wii started making tons of noise while spinning the disc and is now probably Wii > X360 > PS3. I have a feeling my Wii will die soon but it's been like this for almost 1 year, so it may work forever just really loudly.

DS is only the quietest if you have the volume off, otherwise it generates alot of noise! :)

Speaking of the fans in the ps3 does anyone know how to get the fans to spin the other way to blow the dust out and also does the 360 have this facility aswell?

360 - Standard play - Noisiest (Noise Factor 10)
HDD Game install - really very quiet. (3)

PS3 - All modes - really very quiet (3)

Wii - All modes - Heck is this thing even on (2)

My Wii was unnoticeable at purchase, but its developed some problems with disc reading, it sometimes makes a bit of noise now :(

There's probably an issue, mine stopped reading Brawl cause the the dust/smoking.  I sent it in they found an issue with the drive and replaced it, even my loudest game CoD W@W is silent, it used to make so much noise reading that game before Nintendo fixed my Wii.  They will fix your Wii for free if it stops reading Brawl, so get a chain smoker to blow their smoke directly into your Wii.

My original 360 was loud but I got one of the newer ones and it's quiet as can be. Add to the fact the only time I ever use discs on it is when I'm installing a game, I rarely know it's on.

My PS3 (80gig BC model) on the other hand sounds like a jet engine and is even louder than my old 360.  Oddly enough it's usually the loudest when I'm watching a movie (DVD/BluRay), not when playing a game.

-edit-

Wii is quiet too, though occassionaly I can hear it.

From all my experience with each (not just my own consoles but friends) so far I'd say the order is

1 - Wii - silent basically

2 - PS3 Slim - pretty quiet

3 - PS3 phat - okay volume but can get loud after protracted gaming session. Quiet when playing media such as BR, DVD, etc.

4 - Recent 360 models - still pretty loud, but quieter than...

5 - Original 360 models - so loud the volume was a negative factor in my consideration of whether to buy one

Yea, I don't know if that will work now. I decided to mod my Wii since I figured it was likely to break and I just wanted to mess with it. Turns out its super easy and rather interesting. So, if it breaks, I'll try backing out the soft mod, but I don't know if I can or not, but it still reads all my discs (for now). To bad modding a Wii doesn't really provide all that much use other than for pirating, and the pirates already took care of writing all the software needed to pirate. I really don't know why I did it