I am unable to create tickets in the themes trac, so I'll post it here: In a multisite installation the featured image of a post or page doesn't work.
Steps to reproduce:
- Install WordPress
- Download the TwentyTen theme
- Post a new page or post on the new site, set a featured image
- The featured image works
- Create a multisite setup
- Create a new site within the network admin
- Create another post or page with a featured image in the new site
- The featured image doesn't show up, instead the default image is shown
Strangely the featured image from the first post in the main site still works, but in the second site it doesn't.