I never understood why people referred to the PS360 as HD Twins. Now that the WiiU is launching this fall, and much of its announced games are available on the two aforementioned consoles will people refer to them as HD Triplets?

No because the wiiu's main control scheme is extremely different than the HD twins. It's more like their younger little cousin or the guy with one arm that shows up late to the party.

said yes but honestly who cares.... it doesn't add or take anything from any of the consoles in the market....

this.

I really don't put the wii or the wii U in the same category as the HD Twins. It brings a different experience to the table.

The 360 and PS3 were going head to head all generation but the Wii was just doing it's own thing. I'm sure the WiiU will be the same considering what I've seen.

They were called the HD twins because outside of minor differences, they were pretty much the same. One was a little more powerful, one was a little cheaper, each got a handful of their own exclusives (not counting first-party), and their markets were pretty much identical (with FPSes pretty much dominating).

The only real differences were that the PS3 had a stronger Japanese presence, whereas the Xbox 360 had a stronger American presence, in terms of support, and that their later motion control systems worked differently from each other.

What sets the Wii U apart, other than first-party things, is that it has unique controls as standard - this practically guarantees a variety of exclusive titles from most third parties.

I think the "HD Twins" thing started because the Wii was clearly not in the same graphical league as the Xbox 360 and PS3. It was a way to differentiate between HD games that could not run on the Wii unless gimped.

"HD twins" started to justify why Wii wasn't the best selling console numbers wise.

It was a reason for developers to justify to their stakeholder their multiplatform developements over developing on the leading platform.

From my perspective, it started as a veiled insult towards the consoles from Nintendo fans. Really the same thing with PS360, to represent and gently mock the fact that the two consoles were trying so hard to be so similar to one another