I've tested quick-cache on a fresh wordpressMU with 2 sites like this :
- blogs.wpmutest.xxx : the main blog
- sitemu1.xxx : another blog
The sitemu1.xxx blog is mapped using Domain Mapping MU plugin.
If I install QuickCache, I can see the settings, it adds correctly the "define" in wp-config.php and the advanced-cache.php in wp-content.
I can also save default options after activating the plugin in the network admin part of the wordpress MU.
But if I logout I can't see the comment at the bottom of the code source mentionning that quick cache is working.
Is the plugin broken with WordPress MU ? It has worked in the past with wordpress MU 3.0x and quickcache 2.2.X, so tell me please :)