glemigh, thanks for the link to that article. Based on the following quote, I think the Zend Framework ACL is a RBAC:
RBAC differs from access control lists (ACLs) used in traditional discretionary access control systems in that it assigns permissions to specific operations with meaning in the organization, rather than to low level data objects. For example, an access control list could be used to grant or deny write access to a particular system file, but it would not say in what ways that file could be changed.
With the Zend ACL you can assign roles to resources, but you can also add privileges into the mix. Take the file system example above. With the Zend ACL you can grant or deny privileges (write and/or read etc.) to a resource (the file system or a file) for a role.