Does this sound familiar to you? At some unremembered point, you stumble across some new technology breakthrough, a potential product or technique - let's call it technology X.

Soon, there's a general buzz about it. You keep hearing about the wonders of technology X. Tech X is not quite here yet, not today, but the analysts and journalists who have seen demonstrations of tech X (in a tightly controlled, highly artificial setting) tell you this is the next big thing.

But first, tech X needs a bit more fine-tuning. Oh, and it needs the infrastructure to develop a bit more to support it (read: faster chips, broadband Internet access, a certain critical mass of devices, whatever).

You harbour a small satisfaction about having heard about it at the start. You await its glorious, post-beta, fully developed arrival into your desktop/home/ handheld/handset.

We all know that story, have heard that song. It lures us because we love to hear it and be filled with wonder and expectation and the thrill of possibility. Funny how we fall for this, over and over, despite the evidence almost every time that tech X will not materialise in its predicted timeframe. Sometimes it indeed turns into something indispensable - the mobile phone, the Palm Pilot, the Web browser - but often not in the ways we at first expect. And almost always, tech X is adopted far, far more slowly than the analysts predicted.

I have been thinking about this in relation to 3G mobile networks, the ones that will theoretically bring us fast Net access over our handsets, and the ones that have weighted so many European network operators with groaning loads of debt. So much, in fact, that the operators have no money left to build their networks, especially now that market sentiment has turned against the operators.

Recently in New York I heard the senior telecoms people with Cap Gemini Ernst & Young acknowledge that the whole 3G ball of wax will not happen anytime soon and that the next two years will be spent building support for the intermediary 2.5G technology. That will bring better Net access rates via mobiles and more possibilities for ways to use handsets but nothing like the vision we've been given of a high-speed Internet-enabled, m-commerced and video-phoned 3G future.

Industry people I've spoken to seem equally split over three scenarios.

First, 3G never really happens because there's no money left to create the infrastructure. Or, 3G happens at a much, much slower pace. Or, it happens, and fast, because of the enormous impetus for operators to get value out of their hugely expensive 3G licences. Meanwhile, in the US, many of the tech-savvy doubt whether anyone really wants to do lots of Internet-enabled stuff over a handset anyway. There are three reasons they feel this way.

First, people tend to pay flat-rate for mobile connections and there isn't the same possibility as in the rest of the world for operators or third parties to make money from incremental time charges for services delivered over handsets. Second, the screens are too small on handsets. Third, north Americans are used to Palms and Handsprings and iPaqs - Net-enabled devices with bigger screens and more functionality.

The first point may well do in an m-commerce market in the US, although somehow I think business models will change and adapt to accommodate new forms of commerce, not least because the US will be entirely isolated from the rest of the world if mobile commerce develops as predicted in coming years. But in answer to the second and third points, I spent a lot of time on recent trips to the US showing off the "smartphone" I'm using at the moment - Ericsson's R380, which has a flip-up keypad that reveals a screen running the full length of the phone. A bit heavy and clunky, the R380 is hardly a thing of beauty but it has two megabytes of memory and runs a Palm-like organiser and address book, and can synchronise with the organiser on your PC. And it has all that screen space.

The Yanks uniformly gawped at that screen, which has about the same area as a Palm. I showed it to some internationally-known developers, to analysts, and to cynical tech editors and journalists. They all admitted it changed their minds about people using phones for Net access. They suddenly understood that tech X possibility of handsets, 3G networks and mobile commerce - and why the Europeans aren't so off the rails after all.

Several smartphones are available now. They're expensive, as early releases of any new device always are. But these phones and their larger screen "real estate" give a glimpse of a future I think will indeed happen, albeit (as always with tech X) slower than predicted. The phones also make me believe that 3G will roll out over the next few years and that people will want the services many envision just because it will be convenient to get your e-mail on the move, right to your phone, or access Net information when you're not near a PC, and have all your contact and datebook information on one small device.

Maybe I'm wrong. But I think we have some promising and exciting mobile network and handset developments to look forward to over the next few years.