Feed items using XML Base not being rendered properly
http://code.google.com/p/sage/issues/detail?id=6
Sage ships with old Sage project feed at mozdev.org
http://code.google.com/p/sage/issues/detail?id=28
The feed item status bug that Gregory pointed out has also been fixed.
You can download it here:
http://code.google.com/p/sage/downloads/detail?name=sage-1_4_7b2.xpi
Peter