The way it is designed is to create a multi-page PDF with tiled images of the whole photo. Samples shown on the Web site have images that fill an entire wall. If you want, you can also type in a custom page size. This would be ideal for output on wide-format printer or simply to get the resulting image all on a single page. Part of the process also allows you to choose the maximum size of the halftone dot.
OK, it sounds pretty cool so far. Now to tell you about the last feature that will blow you away. The PDF file created by The Rasterbator is made up of a very large number of vector ellipses of varying sizes and possibly various colors. I imported a page I created back into CorelDRAW and there were over 251,000 curves! I've got to admit that CorelDRAW was pretty slow with that many objects on the page.
So, here is the process to create some cool designs using halftones. Design whatever you want in CorelDRAW or Corel PHOTO-PAINT. Export the resulting design to a fairly large bitmap. Run that bitmap through The Rasterbator. Import the resulting PDF back in to get a vector-based halftoned graphic. Did I mention that The Rasterbator is free? If you create something cool, please post a comment and let us all know about it.