The medium and the message - they're not the same thing
Nice article, but I think it would have helped to go just 1 step further.
a digital TV picture arrives on your screen thanks to 2 very independent components.
The way the picture (and sound) is encoded into bits - MPEG2, MPEG4 / H264 - is the the message.
All HD piccies are using MPEG4 as it is very much more efficient than MPEG2. The same standard is used for freesat HD as will be used by freeview HD (and is also used by most other HD transmissions - maybe even all). PCs already handle MPEG4 quite happily, as do such things as a Freesat HD boxes. Indeed many nice things are happening in the PC space, such as Nvidia building MPEG4 / H264 decoding into the drivers for their newer cards (even for linux...)
The second part is the medium - how the digital bitstream is delivered to your display.
This can be carried over a satellite signal or a terrestrial TV signal. Today freesat uses the S1 standard, and it delivers SD and HD pictures. There is an S2 standard, and some equipment supports it, but freesat will not be using it for some time yet. S2 can carry more bits in the same space as S1, but as satellite transmissions are not yet feeling the bandwidth pinch, they do not have a big incentive to change. I'm happily receiving BBC HD transmissions onto a linux based PC, as they are not encrypted or DRM protected in any way.
Freeview today uses T1 only and is all SD, but in a few days will start using (on 1 multiplex only) T2 to carry more bits and deliver HD channels.
The main reason that there is no kit around as yet, is that the BBC wants to DRM the HD broadcasts, but could not just encrypt the data stream (as that is against the BBC charter), so they proposed to Ofcom that they should encrypt the EPG info as a slight of hand way of (apparently) not breaking the charter, while still locking up the broadcasts.
This required that reception equipment be modified to handle the EPG encryption, so until it was known to be in or out, none of the manufacturers could actually start manufacturing kit, getting it certified, getting it into production, and eventually into the shops. As this only got kicked into touch by Ofcom a couple of weeks ago, no kit has yet started through this process.
Of course this whole certification / approval thing is a bit weird anyway - it never used to happen in analogue days, and is really just the BBC, on behalf of ( itself and ) the big media companies trying to control the whole channel (as the media indistry did with DVD encryption).
Finally we get to the picture, and the BBC - in an effort to jam a quart into a pint pot - have screwed down the bit rate on HD (on freesat HD and also the same thing to be on freeview HD), so that their picture quality appears to be significantly poorer than the other HD channels from sky and virgin - not that they will admit to this of course, they believed the manufacturers of their shiny new MPEG 4 encoders when they were told you could get HD pictures at 2 1/2 bits per second.
ho hum, where's my tin hat