I still remember that in the early days of GPRS, the main problem was to get mobile devices that could actually make use of the new network service. The story repeated itself with UMTS where where things became even worse. When UMTS first started, there were lots of networks around but no or only clunky mobile phones available for at least a year or so.
In the meantime it looks like the situation has reversed. Quite a number of 7.2 MBit/s HSPA devices are available, but only few networks yet support ten simultaneous downlink spreading codes and have the required backhaul capacity to the base station. With HSUPA it is quite similar. A number of devices, mainly USB sticks, are available on the market today, but most networks still lack support. And it's not only in UMTS, where devices are far more capable then most networks today.
Even 2G mobiles now support features that most networks are lacking. The AMR (Adaptive Multi Rate) speech codec is a good example. Widely supported in handsets today, but only used in few networks today, despite the potential capacity increases the feature offers to operators. Or take DTM (Dual Transfer Mode), which enables simultaneous voice calls and Internet connectivity for GSM/GPRS/EDGE devices. Again, many mobiles support this today and it could be put into good use especially with feature phones. However, I haven't seen a single network that supports it in practice.
A worrying trend. Are the standards bodies specifying too much?