I think that's a pretty general rule across SE sites, that you should disclose personal connections whenever you reference something you're involved with.
Beyond that, I don't see anything wrong with linking to (or otherwise referencing) your own content, as long as it's relevant to the question being asked or answered. For any given question, there's a decent chance that people who are qualified to answer it will already have done some work in the subject, and it'd be a shame if they weren't able to cite that work freely. Plus, it seems fair that people who contribute a lot to the site can be rewarded with the occasional opportunity to plug their own work.
On the other hand, it certainly is possible to abuse the ability to post self-promotional links. When an established user does it once in a while, that's probably okay, but a newer user who links to their own content in a majority of their posts, regardless of disclosure (but especially if they don't disclose a personal connection), could be considered to be spamming the site, which is not allowed. If you see that sort of thing happening, and if it's clear that it's not just an isolated incident, don't hesitate to flag it as spam or for moderator attention.
