Don't hate me, this is the third report for me in less than 48hours. Anyway, I installed the _sitemap skin and tried to generate a sitemap for google of all the blogs. So I set blog #1 to aggregate blogs #2, #3 #5 & #6 (#4 is the linkblog). I try accessing /index.php?blog=1&tempskin=_sitemap and I get nothing:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
</urlset>

However if I do the same thing with the _rss2 skin, I get what I want, all the posts from all the blogs.

In any case, since Google accepts RSS as sitemaps, this is not all that urgent, but I thought you should know.

Cheers!