I hope everyone knows there's nothing binding about this page. It's just a page for extension authors to list their custom namespaces in order to avoid conflicting. Declaring 500-599 will only be used for custom site namespaces and any extension using them is wrong is just silly. Like Jack points out, SocialProfile has been using its 500-range namespaces for quite some time, and there's nothing wrong with this. He should be allowed to add his namespaces to the list like every other extension. Looking at the discussion above, I hardly call that a consensus. It's barely even a discussion, coupled with the fact that this is a very very low traffic talkpage. I don't see any developers involved in the discussion, and I don't remember the discussion being advertised on wikitech-l or mediawiki-l as I would expect.
This post was posted by Peachey88 (Flood), but signed as ^demon.