How tall can a man made and comfortably inhabitable structure be within the limits of current engineering and material technologies?
I wold say there are a few factors, if you will allow for the building to be infinitely large as in surface area at the ground, they I say limitless, with one catch…the taller you go, the heaver it gets, the heaver, the more heat from frictions, and the more heat, will eventually melt the cement foundation right out from under it.
Friction? What friction? What two substances are rubbing against each other to produce friction?
Howstuffworks says:
Not a definitive answer, I know.
Does anyone remember a proposal (IIRC, Japanese) to build an elevator to an orbitting building?
I do not think friction implies rubbing, but rather oposing forces, I ice cube will melt faster if you put a heavy weight on it, I am totally making educated guesses on this 
I am Captain Google …
Again, not like it answers anything definitively but this is a cool little article at a cool little site …
I recall hearing that Poland was sending a manned spacecraft to the sun. Don’t worry, they’re going at night.
I read somewhere a while back a mile high building is now possible.
No, I don’t remember where I read it. So don’t ask for a cite.
As best I can tell, these two statements have nothing to do with each other.
Friction does involve motion.
Ice cubes melt under pressure because of the negative slope of the solid-liquid line on the phase diagram for H[sub]2[/sub]O. (This also indicates that solid ice is less dense than liquid water.)
Finally, long before the concrete melts :D, I expect you will exceed its compressive strength and simply crush the foundation (or the support members).