One of my complaints was the Zend_Cache did not accept lifetimes on a per object basis, but rather the lifetime was at an application level. I just received notice in my inbox that the issue has been fixed! The change is currently in svn, and should be in the 0.80 preview release. Thanks go to Fabien for the fix.
You can download this latest version of the Framework (0.7.0) from the Zend Framework website.