I've never seen a question from Meta included in the "Hot Network Questions."
I'm talking about the site I'm posting this very question to, not site-specific Metas.
If Meta SE is currently excluded, then I suggest that it should be included.
(Edit: Or Patrick's suggestion in his answer, which may be even better, IMO.)
My reason for this view is that users from all sites should be encouraged to participate in Meta, as it concerns them all. Some users may not even be aware that Meta SE exists. (They may thus post general, technical questions in their particular site's meta instead.)
If they can be shown questions about the details of Darth Vader's personal life (which I personally enjoy, btw) then I think they should also be shown "hot" questions from Meta SE. Questions on Meta SE also concern whatever other site(s) they are using.