Cultural appropriation is always one of those difficult topics in modern Pagan and neo-Pagan practice. I know it's one that eats up a lot of my thought cycles, especially when I try to explain to someone just what my path and calling are. Kulasundari Devi is a guest writer over on The Wild Hunt blog (do you have it in your feed? No? Why not?) and she addresses the topic very nicely today. The focus is around the incorporation of Hindu deities into Pagan practice, but the general ideas and philosophies could be used to address any time one is drawn to a culture of which they aren't a part.
At the least, it's worth a read and some thought.
http://wildhunt.org/blog/2010/06/hinduism-indo-paganism-and-cultural-appropriation.html