feedblitz is targeting feedburner users directly. They actually now how to spell RSS and do things like reporting on your RSS usage. They're kind of like feedburner in that you're supposed to not publicize the feed coming directly from your site. You're supposed to set up your blog's feed to go into feedblitz and they'll give you a related feed to give to the outside world. By having everyone go through feedblitz, they can compile statistics of how many people from where are downloading your feed.