Personally I like the Apple Fool's submissions. I've even been tricked by a few. It's all in good fun and puts some heart in the cold machine that is technology news.
+1 for articulating an excellent standard for April Fool's submissions: If you are tricked by a post, it's worth submitting and seeing what other people think.
But honestly, anyone looking at a post and seeing right through it, don't bother submitting it to HN. If it doesn't fool you, it isn't that interesting.