What many SEO engineers don't realise is that directory owners are also actively involved in SEO, the successful ones have been around for several years and understand exactly what they are doing. They are fully aware that their directory is at least in part an SEO machine. I'm one of "Them", I own and run over a dozen directories, listed at http://www.hosted.co.nz/links/Internet/Directories/, that accept public site submissions; my oldest directory has been running since late 2006, my newest ones have been running just over a week.
You and the directory owner both want to get quality links into their directory and as long as both sides play by the rules, you are allies and not adversaries. This article is to explain the real rules and why those rules exist.