I know that the core of linux is a kernel, a piece of code that sits between the hardware and the user or system apps and services.

Linux kernel is the base of many distributions.

Now: can this kernel be used to create a whole new distribution or operating system, that use it 'as is'?

Can someone get a new running system that works with 3g, gsm, BME, 3D... just as they are? I mean not being a mod, hack or enhancement of Maemo, but a new operating system, that loads the same drivers that Maemo loads, but with a different approach...

In theory yes.

Unfortunately though the fono Drivers are closed source so it has not really been successfully possible hence the long delay with getting Calls to work in NITDroid and they are forced to write there own.

Now I do remember hearing that the Kubuntu team had calls working but the last time I was over on that site, the OS was still buggy. Looks nice though.

Nemo Mobile also has calls working if I remember correctly but am not 100% sure about that since when I received a call on it, it opened and then restarted the phone.

Does any of the OS components (telephony, networking, 2D/3D graphics...) talk directly to hardware?

Or do they use APIs? because if so, it should be easy to create that OS through the use of existing APIs.

Does the dbus provide an use for all of that?