In this ever-changing industry of ours, it is comforting to know that some things never change.

Anything Panasonic does Sony will try to do better, and vice versa. Anything Sky does, Virgin will then promise to do. And Virgin's press relations are consistently erratic and in general useless.

Panasonic and Sky made the early running on 3D. So it was inevitable that Sony and Virgin would quickly get in on the act. It was also inevitable that Sony would do it a whole lot more efficiently than Virgin.

Sony gave impressive demos of 3D at IFA, with the promise of 3D Bravias for 2010.

Now from Sony comes the new 3D Vision newsletter, which reminds us that the Blu-ray Disc Association plans a standard for 3D BD by Christmas. Separately, there's leaked news – now confirmed by Sony – that all existing PS3 consoles can be upgraded next year to play 3D games.

There's no word yet on whether the upgrade will also handle 3D movies and what kind of TV display will be needed.

As a general guide, there are two basic approaches to 3D displays – albeit with a lot of variations on the basics.

The Panasonic approach, also used for Sony's Bravia system, is to show a very rapid succession of full-HD 1080p left and right images, while the viewer wears expensive active LCD spectacles that rapidly shutter the left and right eyes.

The Sky approach is to show the left and right HD images at the same time, but on interlaced lines on a screen covered by an invisible lattice of polarising filters. The viewer wears cheap passive polarising spectacles that let the left eye see only the left image lines of the picture, while the right eye sees only right image lines.

The Panasonic/Sony approach gives higher resolution HD, but a new TV is needed to cope with the high display rate and the spectacles cost up to £50 a time and need batteries. At IFA, a similar 3D demo by Samsung was showing only in 2D, probably because the spectacle batteries had gone flat.

The Sky approach needs a new TV set with built-in filters that compromise quality, but not as much as expected, because the brain does a good job combining the images. The spectacles are cheap and need no batteries.

It came as no surprise to learn - but only second-hand from garbled reports - that Virgin is promising 3D to rival Sky. I saw no press release or press demo, so played the punter and visited the new Virgin Media store in London’s Oxford Street.

The store sells phones and cable and broadband package subscriptions but is small - smaller even than the Virgin Media section in the now defunct Virgin Megastore nearby, which became Zavvi before closing early this year. A large screen 1080p JVC LCD on the store wall, fed by a Samsung cable V-Box, was showing a BBC HD demo programme in 2D.

But a large sign over the screen promised "Let us entertain you - ask for a demo" with a rosette label promising "3DTV ask for a demo".

Asking for a demo involved waiting in line for far too long behind customers buying and setting up phones. Dutifully, I persevered until one of the five assistants was free, when he courteously agreed to give us a demo.

This involved taking a remote control and Real D polarising spectacles from a behind the counter, switching the TV to "side by side" display and running a passive polarised 3D demo (credited to Focus Features) from the V-Box.

The demo included a trailer for Coraline and the effect was good - similar to Sky's demos with a similar system - but there was no sound and nowhere to sit. So I did not stay long.

This is doubtless good for Virgin's phone sales, because the salesman had to stay by me in case I nicked the specs.

"There are no firm plans for a 3D service," he told me when I asked. "We are investigating."

As I say, anything Sky can do, Virgin will try to do later.