Yeah these are extremely embedded devices so you don't expect any kind of upgradeability, you just have to be grateful for what we do have:

* full-size sd => mini-sd adapter or full-size sd => micro-sd => mini-sd adapters.
* USB OTG cables
* DIY accelerometer
* 3rd party usb chargers

not to mention all the amazing software "hacks"

The openpandora project can certainly be looked at as the next internet tablet. It has an OMAP3 processor, graphics that support opengl 2 and more. Personally the only issue I have with it is that it's a clamshell form factor and the screen isn't rotate-able : which makes it hard to use while walking plus no portrait mode. Of course it runs Linux and even a custom window manager ala Maemo's hildon.

I've had similar thoughts with my NAS but anything with an ARM architecture (and keep in mind pretty much all ARM processors are different so no compatibility) everything has to be compiled against that particular processor.

Hopefully Nokia doesn't disappoint with the N810s successor (the N97s specs make me optimistic).