@drago1 .. you have posted two confilcting statements.
Frist you stated that if *the vertical resolution* ... And you even wrote a specific number (1440)
Next you stated that if *the DPI* ...
.. there is no simple correlation between monitor resolution and DPI (as monitors have different size).
I know that Mac simply operates such a factor2 for 'retina' displays. Win8 does not. It will simply scale to fit the monitor and it may result in a zoom factor 1.2 1.4 ,1.5 or whatever (and @Chris .. that interpolation could result in fonts appearing somewhat blurred) . And there also is a user setting for zoom in the (traditionial) desktop context menu .Addtitionally individual applications may be zoomed (with two-finger gesture on touch screen or touchpad) if they are built for it (I tried to find the docs in MSDN - cannot right now but there is one specific Windows API function call that needs to be made). Try zooming Notepad or whatever in Win8 like this: put two fingers on the touchpad and spread the fingers (few non-Microsoft applications support it currently, but most of those that ship with Win8 do - also those that run in the traditional desktop, including Control Panel, Windows Explorer etc. ).
@Chris .. on my stationary (as said 27" - 2560*1440) I think that everything - icons, fonts etc. - is too big. Gnome is wasting my desktop space here. Maybe it wold be Ok for a cheap TV set and similar not very sharp screen - but not for a premium quality monitor as mine.
BTW: I was asking what logic Gnome uses. ;-)
-- Peter