Man, there's some profound stupidity in this thread. And I certainly don't mean to offend anybody by saying that well, except the profoundly stupid people, but they can't follow what I'm saying anyway, so it's all good.
The biggest stupidity I've seen by far are the people who seem to think that if you had an HDMI port on your Mac, you could plug in a Playstation and play Playstation games on it
or something? It wasn't entirely clear. Are those guys serious?
Anyway. A computer display and a television are different things. They might look similar on the outside, but on the inside they're very different. Is this how it should be? I don't know, that's a different argument. But it's how it is, because of radical (and entirely historical) differences in signaling standards.
HDMI was designed for use with televisions. Recently it's been tweaked to make it suitable for home cinema. Whether it will be successful there remains to be seen, because that market's so new.
DisplayPort was designed for use with computer displays. Right now, DVI is still the universal standard there; HDMI is not, nor does anybody think it should be. DisplayPort is intended to address many of the shortcomings of DVI, but it's still new. As anybody who remembers the VGA-to-DVI transition knows, these things take time.
Whoever it was who said that it'd be great if we could replace all of these cable and signaling standards with a single unified standard I think it was more than one person, up-thread was absolutely right. It would be great. The problem is, we've tried many times and have never succeeded. The "U" in "USB" stands for "Universal." It was supposed to replace all low-speed serial interconnects. Later it was tweaked (like HDMI is being tweaked) to replace high-speed serial interfaces as well. But it had some fundamental flaws (it wasn't good for isochronous transport, which meant video cameras stuck with Firewire) and it hasn't kept up, so now we have things like Firewire 800 and eSATA for storage, and Firewire is still the dominant interconnect for DV, DVCPRO and HDV video cameras. The universal interconnect wasn't.
As we transition away from analog signaling to packetized digital signaling everywhere (as with DisplayPort to name one example), the potential that we might replace all our cables with a new universal plug becomes more real. The problem with that is that interconnects need to be inexpensive, which means they need to start out as slow as they can be. Later, they need to get faster as economies of scale kick in. A serial interconnect struggles there, because you reach a point where radio-frequency interference is an issue. DisplayPort addresses this with software, and it seems to be a good fix, but we won't really know until the installed base is large enough to draw generalizations.
As mentioned above, Light Peak is promising indeed, except for one huge problem: No electrons. Optical signaling can carry just about any type of information you could imagine, but it cannot carry power. Period. You have to move electrons in order to transmit power, and electrons don't flow through glass. Well, at least not in a useful way.
So what's the answer? A hybrid cable that's got nano-scale reflectors lining an optical fibre, alongside a pair of copper conductors to carry some arbitrarily high amount of current and voltage to satisfy all imagined future power requirements? Great idea, but for it to truly be universal it'd have to be massively overbuilt, which would make it even more expensive than small-radius optical cables would already have to be.
We are starting to see the light at the end of the tunnel, though. Twenty years ago, people talked about "peripherals." You had a home computer (which was identical in every respect to a work computer, and for that matter was basically identical to a workstation, because a computer was a thing and we made them to be generic instead of application-specific), and then you had "peripherals," things like printers and stuff. Your speakers were a peripheral, because computers didn't have them built in yet. Companies pitched the idea of giving away personal bar-code scanners, which were computer peripherals, in order to sell advertising through them. (This was before the URL was a popular thing, and long before Google obsoleted the URL.) You could go to a store and see row upon row of "peripherals" that were designed to plug into your computer and do specific things, and many of them had their own plugs and sockets.
That nightmare began to fade away because of two things: first, plugs-and-sockets standards began to congeal into these vague lumps *VME, PCI, VGA, DB9, DB25, whatever. And second, more and more the world sort of collectively realized that nobody gives a **** about handheld scanning devices. So the sheer volume of interconnects went down, while at the same time the sheer number of useless things companies were selling to plug into your new-fangled "computer" plummeted.
Then wireless came along, and things got a bit simpler still, because for many applications were were able to just let go of the notion of plugging in entirely. We're going to continue to see more things transition from wired to wireless, once we figure out how to deal gracefully with unreliable connections.
But connecting a computer to a display still takes a cable, and might always. Shipping that many gigabits per second through the air pushes the limits of what physics allows, and while it might be possible, it's certainly not going to be easy. There's also the question of whether it'd be worth it to try. Instead, it makes sense to come up with an interconnect that's fast enough today but scalable for the future, that can be daisy-chained to drive multiple displays, that has built-in support for optical signaling for long and relatively inexpensive cable runs, and that's easy enough to implement that we don't have to sink eighty bucks into each chip we use.
That's basically what DisplayPort is. At least, that's what it's intended to be. Whether it'll succeed is, again, yet to be revealed. But DisplayPort and HDMI have different goals, and they serve different needs, and frankly if you can read this whole long ramble and still not get that, then I'm just not sure what else I can tell you.
