Remember that all these phones have the same resolution so, in reallity, a smaller screen means smaller pixels and lower dot pitch so it will seem more detailed and sharper. It's like HDTV, now we all have our 42"+ tv's and everyone is getting excited about HD, all it has really done is brought us back to the definition of 20 yr old 14-20 inch TV's. Actually definition is the wrong word for this reason, that's marketing for you! They should be called hi-res TV's.
Of course I sit a lot further from my TV than I do from my phone so taking perspective into account the pixels seem about the same size but at the same time, take your Desire and hold it 10% closer to your eyes (1inch?) and it works out exactly the same effect as the HD2 etc etc.
While all these devices have a *resolution* of 800x480, a 3.7 in screen @ 800x480 is higher *definition* than a 4.3 inch screen @ 800x480.
The point I am trying to put over is that a small difference in screen size makes no difference at the same resolution in the real world, it's all about bigger numbers in technology equaling higher sales numbers! Give me a bigger number for RAM, Processor speed, data speed etc etc, even resolution, but I am not that fussed about small differences in screen size.
Another thing that I thought about recently is that, on the other hand, if they can now get 800 horizontal pixels on a 3.7 inch screen (about 2.8 inches wide horizontaly) how high will the resolution on my 42" telly be in 5 years, If they cram as many pixels into the same space it scales up to about 8000+ horizontal pixels! Just give them time to cram that much data into the signal and were off!