Note that I've not included the 'Suretype' style devices, including the imminent Nokia E55 and Sony Ericsson P1i/M600i - this article is about real qwerty, i.e. one letter per key!
It's also worth noting that I typed 90% of the text for this feature ON a qwerty-equipped Symbian OS smartphone (while seated in a deckchair at a music festival!) 8-)