Here's the rundown:

1) Loli, shota, and toddlercon images are blocked for users below Gold level (regular Member users).

2) You can still upload these imags as a regular member, but you will not be able to see the images. It's your choice to decide whether this makes you want to no longer upload them.

3) Please do not ask for special exemptions or anything like that.

4) You get invited by contributing to the site. Tag edits, new posts, translation notes, programming help, etc. Don't ask a mod for an invite, that will have the opposite effect. The mod will find you if they want. You can also donate to obtain a privileged account. See here for details. See also forum #7207.

5) These are the only tags that are blocked.

I'm locking this to avoid more of the same old debate, but if I missed anything that would be useful in this post, please PM me and I'll add it.

Edited
- 7/25/08 to update list of types (contributor, janitor) in point #1.
- 6/30/09 to clarify it applies to shota as well and mention the donation approach.