If all your package is going to do is hold a single blessed reference to a hash, creating a special OO configuration package seems like an overhead inefficiency, both in terms of programming and execution. However, if the rest of your program uses OO design, you may want to. Instead of building a single config var get() method for each var, you might consider a permutation on the AUTOLOADER idea that allows you to specify a list of keys, and returns the values in that order. You might also consider not having a new() constructor to prevent polymorphous instances of configuration, and then write all methods as class methods.

I haven't been impressed (on very cursory inspection) with what I've seen for config modules on CPAN yet, so please write a review if you use one and get a decent understanding of its strengths and weaknesses.

update: on reviewing AppConfig, it sure looks like a robust module, worth the time to learn to use if you have more than trival configuration concerns.