Ideally, it would be a bit of a hybrid of existing devices.
3.5-3.7" 800x480 capacitive touchscreen
slide out gaming controls (I'd settle for an on-screen keyboard for the smaller form factor, though I checked, and the keyboard from my E71 would fit between the d-pad and buttons of my Game Boy Micro, so a physical keyboard is possible here. I have absolutely no problems with my E71's keyboard.)
3.5" headphone jack plus TV out
MicroSD slot (full size would be nice, but not very realistic)
Ideally it would have about 8GB of built-in flash, too, but this is a "nice to have"
OMAP3 based chipset
HSPA on 850/1900MHz frequencies. 1700MHz (AWS) would be nice but unnecessary, no Canadian providers use it (yet).
Linux-based firmware without silly vendor restrictions, ideally Android, but Maemo 5, WebOS or MobLin would be ok too, in descending order of preference.
5MP or better camera, similar to the higher end N-series phones. Megapixels aren't hugely important, but a good sensor and lens is. Xenon flash would be preferred.
Basically a hybrid of a Pandora, an N-series phone, and an Android phone. This would basically cover any need I could think of and fit in my pocket to boot. Never going to happen, though, so I'll settle for a Pandora and a good phone. This would probably run me well over a grand anyway.