I have no idea how hard those are to get into--I'd heard of 'em, vaguely, and I think I saw 'em on the shelf occasionally--I submitted art because one of the editors wrote me and asked for Sir Bunny, specifically, because he claimed the humor section was badly understocked. Mostly I recall seeing call for entry banners over at GFXartist.
James was impressed, since evidentally it's someplace a lot of the digital artists for game companies he knows submits to, but we're talking about someone that can be reduced to helpless hysterics by a well placed utterance of the word "weasel!" so I dunno. For all I know, 90% of applicants get in. How Expose fits into that broad world 'o art publication, no clue. Anybody heard of it?