This module aims to allow site admins to grant granular administration privileges to "Deputies".
Site admins with the appropriate permissions can select which modules are visible to 'Deputised' users (who have the normal permissions to use the modules settings form). So the Deputies can change which modules are enabled, but certain modules can be hidden from them.
Any hidden modules which are enabled remain enabled when Deputised users make changes.
A common use case is to remove the ability to switch on the evaluation of PHP code.
This might be particularly useful in a managed hosted environment where site owners should have a high level of control, but do not have access to the user #1 account.
There are both D6 and D7 versions of the module.
This module originally included the ability to 'deputise' permissions as well as modules, but it came to light that the Permissions Lock module provides this functionality and more - so the permissions side of things was removed from Deputise.
The current releases are both marked as alpha1 simply to reflect their novelty as full releases.