I don't know if you're aware of this and quite honestly, it's not a big deal to me. It certainly doesn't prevent me from using minishowcase.
But when you are in a slideshow and there is more than one page of thumbnails (ie more than 24 photos in a gallery), the text at the top of the slideshow to indicate where you are is displaying x of 24 photos. Even if you are viewing photo 30 in your gallery. It's breaking down the total number of photos into groups of 24 rather than taking into account the total number of photos.
Is the _MACOSX folder just for Mac implementations or is it required so that MAC users can view things? For example, my site is hosted on Linux. Do I need the _MACOSX folder on my server?