I have just been using Pages, part of iWork.  I saved the file with the wrong name, but decided to alter it in the Finder.  I was very pleased, and surprised, when I noticed that the file name had been changed in Pages as well.  That is, when I used the Finder to alter the name of a file already open in Pages, the file name was changed at the same time in Pages.

Try that on a Winders machine and you will get a sharing violation ...

Chris