The Meta [faq](https://meta.stackoverflow.com/faq) begins:

>If your question is about:
>
 - Stack Overflow
 - Stack Exchange Area 51
>
… it is welcome here.

I have asked questions about Area 51 on MSO in the past, but ever since about September, the Area 51 mods have been encouraging posting meta-type questions regarding the site in the `discuss` section using the `area51-meta` tag (which seems to have been in existence since early 2011).

I'm wondering where the dividing line is.  In broad strokes, what sorts of categories of questions are still appropriate to ask, here on Meta, about Area 51?