No Featured Image option available.

Hi. I can't find any Featured Image option - anywhere on a new site I'm working on.

Fresh WPMU, one theme (Weaver Pro). But, I don't think it;s the theme because even in Twenty Ten I don't have Featured Image option.

I checked in screen options, not there. I checked the functions.php and it seems thumbs is (or should be) enabled.
I have no other themes installed.

Any ideas what I could try?

Martin