Nope, it remains a simple bilinear scale, with the cursor's smallest size being the size at which you get a 1:1 pixel mapping. The best you can do is scale the cursor up to an integer multiple of its smallest size, to avoid sampling errors, but that's quite extreme. My quick calculation is that the 24" Cinema Display has 94.34 dots per inch. Clearly if you scale the cursor up to double size then you get the same effect as if you were viewing it on a 47.2ish dpi screen, which is a lower resolution than the original 1984 Mac.
Furthermore, it seems that no method has yet been discovered allowing third party software to alter the mouse cursor in Leopard. Furthermore, even changing the user interface scale (which is possible temporarily with the 'Quartz Debug' program provided with the developer tools) doesn't change the size of the cursor.