How to get data from config.xml of a module

Question

In the module A I need to get some data from file config.xml of modules B and C. Are there any methods or classes dedicated for this?

Especialy I need to get XML structure and values of node <default> so that I can restore default values of system configuration of modules B and C. Below is example from config.xml of Wishlist module:

<config>
    <default>
        <wishlist>
            <general>
                <active>1</active>
            </general>
            <email>
                <email_identity>general</email_identity>
                <email_template>wishlist_email_email_template</email_template>
            </email>
        </wishlist>
    </default>
</config>

As far as I know Magento loads config.xml files of all modules, so I was wondering maybe this data is already cached and can be retrieved from cache somehow? If not, how to retrieve it programaticaly?