Splitting a DVI signal

Do all the DVI versions support splitting off into 2 displays for the purpose of expanding the desktop (as opposed to the same screen on both)? Will any DVI splitter enable someone to use 1 DVI port for a Dual screen display?

i take it from the lack of response that nobody knows..

may sound like a stupid question, but where work they have dell computers using a special DVI port ( i forget what the exact type is) that a splitter plugs into, which then two displays are connected and used to expand the desktop from that single port.

One of my friends says that its just that special video card (with the special dvi port) that is able to carry to signals and that standard DVI ports cannot do that.