I'll chip in my two cents...
Wii: I know for a fact that 1% of the initial shipment of Wii's at launch had the "Green Pixel" issue. There was a trace amount green artifacts in some cutscenes in some games (Res4, for example), and it was determined to be an overheating GPU issue. I had this problem happen to me personally, and I just walked into the NOC HQ (since I live close by) and had my Wii hotswapped for a fresh one. Funny enough, the one I swapped with had a bad Disc Drive issue. I sent that one for repairs (all this was free by the way) and when it came back to me, it had another bad disc drive in it. After walking into the HQ again and inquiring about it, they informed me there was a shipment of bad disc drives and any "repaired" Wii's for that month had the issue. Again, I got the issue fixed and have been a happy camper ever since.
I have a friend who had a bad Flash Drive issue in his Wii, and rarely his data will get wiped. That's another issue, but again it's incredibly rare and he's the only case I've heard of it (he didn't think it was covered in his warranty and didn't get it repaired, even though it was covered).
Currently, I've heard nothing about Wii's randomly failing.
PS3: I remember hearing at launch that the failure rate of PS3 was 5-8%. I have no idea what the YLOD is, but I've never heard/seen a PS3 fail since after launch until up to this point. They seem sturdy and reliable (save this new YLOD issue)
Xbox 360: The failure rates of the 360 have been dropping ever since launch, but are still incredibly high in terms of quality standards. For the fitrst year and a half the rate was 33%. It fell to 30%, then a little longer after that 20-25%. The lowest and most recent rate I've heard was 15%, but that does not include the E74 issue.
I have 7 friends who own 360's, and every last one of them has had to get theirs replaced at least once. One of them had to get theirs replaced 3 times. All the other guys are pretty much just "waiting" for theirs to die again.
By life end:
- Wii- 100 million+
- Xbox360- 35~40 million
- PS3- 30 million
- PSP- 30~32 million ------------- FAILURE
- NDS- 85~90 million (Skeptical) - FAILURE
- NDS- 100 million+ (Optimistic) -- Success!









