Is there a is_user_logged_in() for multisite?

Yes, and no!

The way users work in a multisite scenario is that there is a single pool of users, who are then associated with blogs.

So, logged in status is common across all the blogs, but you can use is_blog_user($blog_id) to determine whether the current logged in user is a member of that blog. An example:

if (is_user_logged_in()) {
  if (is_blog_user(4)) echo "Current user is a member of blog 4";
}

Codex page for is_blog_user()