Is file.rename() atomic?

[Jacek Furmankiewicz]

   void rename(in char[] from, in char[] to);
        Rename file from to to. If the target file exists, it is 
overwritten.

        Throws:
        FileException on error.

Just wanted to know if this operation is atomic?
or does it depend on the underlying file system?

In short, in the file nanoseconds/milliseconds that this 
operation is occurring is it possible for someone else to be 
reading the same file and get a dirty read (i.e. with only half 
of the contents overriden, etc)?

Thanks