Zend certified PHP/Magento developer

How to get product’s category?

Just as the title says, how do I get a product’s category name or id when I get that product’s information?

I’m querying for a product’s information via catalogProductInfo, and I am also passing in a list of additional_attributes (which includes categoryId). However, the value for every product, no matter what, is:

"Array"

My hope was to at least get the categoryId and then plug it into catalogCategoryInfo to get the information and stuff.

How do I get catalogProductInfo to return a category value I can actually see or an category id?