I've added MPTT to the product category and removed the recursion. Although I did leave in the old private function names in case some people were using them on the sly.
Here's a link to an article about the pros and cons of it:
== http://www.sitepoint.com/print/hierarchical-data-database == Storing Hierarchical Data in a Database
I thought Satchmo shouldn't go without some method of retrieving rows with a single query. I'm working with some larger category trees than the sample store data and thought this might speed things up since the category tree is frequently used.
Now getting children and getting parents is a single query, no recursing down the tree and building a large function stack and fetching the items one by one.
Reported by hkpark