The cut function is implemented in Lion and later as a result of modifying the paste command. If you copy a file as usual but instead hold down the ⌥ key in addition to the normal paste command - it retroactively cuts the original files as well as placing them in the new destination.
⌘+⌥+V = paste + cut in Lion.
This makes an accidental cut and no subsequent paste event less likely.
You can also use: right click + Copy then Option + right click + "Move Item Here"
On Snow Leopard and earlier, the cut function is not part of Finder.
The thing that seems to be different is that CUT on OS X means it's gone now. Whereas cut on Windows means text goes away and files get copied for cutting on paste. The implementations seem quite similar for filesystem cut/paste operations in practice.
Assuming it's not a "patent thing", one could speculate that this is a "do no harm" design standpoint. Why cut something and then potentially lose or misplace it? Imagine the harm if you selected a few hundred files to copy them (or duplicate them) but inadvertently hit the X key. Instead of forcing you to realize a cat or toddler has cut a whole folder of files, the cut only happens when you paste with the option key held down to paste and then cut in one action.