Revoke an applications access to keychain passwords
security is a command-line program which can access/manipulate the keychains.  The following command will output a long stream of text, but it contains the info you're looking for.  You just need to know how to look for it.

security dump-keychain -a login.keychain


This is an example of a keychain entry without any specific access controls:

access: 2 entries
    entry 0:
        authorizations (1): any
        don't-require-password
        description: &lt;NULL&gt;
        applications: &lt;null&gt;
    entry 1:
        authorizations (1): change_acl
        don't-require-password
        description: &lt;NULL&gt;
        applications: &lt;null&gt;


This is an example of an item that only iChat has permission to access:

access: 3 entries
    entry 0:
        authorizations (1): encrypt
        don't-require-password
        description: &lt;key&gt;
        applications: &lt;null&gt;
    entry 1:
        authorizations (6): decrypt derive export_clear export_wrapped mac sign
        don't-require-password
        description: &lt;key&gt;
        applications (1):            0: /Applications/iChat.app (OK)
    entry 2:
        authorizations (1): change_acl
        don't-require-password
        description: &lt;key&gt;
        applications (0):


If you only want to search for a specific application, then it is probably easiest to just send the output of the above command to a file, and read through it manually to search for your application string to find out what items it has permission to use.