As usual, rampant over-speculation
The rumour simply states that Apple is ordering LED back-lights for 13.3" LCD screens.
From this, you guys manage to divine some incredible ultra-portable with SSD's, no disc-drives, &c., &c., &c. (ok, I know the "no optical drive" rumour has been floating around for a while, but still)
Lets consider a few points: 13.3" is the current size of the MacBook screen. Logic would suggest that the MacBook is the laptop destined to receive these new back-lights -
no new model is necessary to explain this information.
"
Ahhh, but..." I hear you say "
what about the aluminium rumour?"
Ignoring the fact that that is a
separate rumour from the current information, we can consider the following recently updated Apple products: the iMac, and the iPod (Classic). Both have switched from the white/black plastic to anodised aluminium. The only product still featuring said plastic in Apple's line-up is the MacBook (and, admittedly, the Mac Mini & Apple TV, but only on the top, which is presumably to facilitate Wi-Fi and Bluetooth signals).
We can surmise from this that Apple
may, following the current trend, transition the MacBook to aluminium enclosures, which would be slimmer than the plastic, and, combined with the slimming effect of an LED back-light, would make the MacBooks noticeably slimmer. How slim? Well, you'd have to ask an engineer - but considering how they harped on about how "amazingly slim" the new iMacs are at launch, they obviously think it's a big deal. Personally, I don't really see that the 1/2" makes a big deal on a desktop, but the utility of slimness in a laptop is obvious.
Now, for a bit of further speculation; I suspect Apple will make the new aluminium MacBooks available in the same range of colours as the current crop of iPod nanos and shuffles, because that's "fun". The MacBook Pros, at the same time, may be made available in the same black as that of the iPod classic, though I doubt they'll be made available in other colours, as bright blue laptops are "not professional". Those of you wondering "
why shouldn't I be able to get any colour I want, if I'm paying for the more expensive model?" would do well to wonder that about the iPod classic, as well.
Possible objections to this hypothesis: "
Aluminium is only for PRO products!"
I would be surprised if anyone still actually believes this, but then, people used to bring it up all the time in the aluminium iMac speculation threads,
despite the existence of the aluminium Mac mini. Simply put: you're wrong.
"
But having all the laptops as aluminium would confuse the product lines!"
Whilst I'll admit that there almost certainly
are people out there that would be too stupid to tell the difference between MacBooks and MacBook
PROs if they were to be made of the same material, chances are these people would either:
A. be too stupid to operate a computer anyway, so it doesn't matter.
B. end up buying the higher-spec'd Pro model unnecessarily, thus delivering more money to Apple,
C. end up buying the MacBook that meets their needs, or
D. somehow set themselves on fire whilst being bewildered by the automatic doors at the Apple store, and thus never manage to make their purchase anyway.
"
Aluminium wouldn't work on a laptop, because it would interfere with Wi-Fi!"
It works on the MacBook Pro - obviously they've found a way.
"
The rumour CLEARLY SAYS "Ultra-Portable""
Just like those rumours of resurrected Newtons, end-of-life'd Mac Mini's, 3G iPhones for Europe, &c., &c., &c....
P.S. If Apple does end up releasing multi-colour MacBooks, please, please,
please don't advertise your ignorance by lauding it as "
an exciting industry first!" because even Dell's
doing it these days... (not that I'm suggesting that they're doing it
well, mind you...)
Bring it on bigger, bolder and with style. Think iMac that runs on batteries.
TV, MacBooks. White plastic is here to stay. For the time being at least. I personally don't think that Apple will ever ditch it altogether. 
