Maybe you could shed some light on the following strange issue:
I have a bunch of WordPress installations (3.1 and 3.2) running on a Debian Squeeze with PHP 5.3.3-7, APC 3.1.3p1 and the development version of your APC plugin. If I update a setting (e.g. timezone) on one of my WordPress instances (single as well as multi-user network), the previous setting will not changed until I empty the APC user cache entries.
The default user_ttl is set to 0 and the apc-monitoring-tool apc.php shows no ttl, too:
wp:4299c432235aea4625c72c0c01d09d89:1:options:alloptions Ttl 0
Any help is appreciated.