In all the countless hours I've spent with php, I've maybe used three or four of these sorting functions. I really had no idea that there is a total of eleven functions used for sorting arrays. Anyway, I'm betting that it may be useful to have these memorized before I take the Zend PHP Certification Exam so here is a brief overview of each one.
He talks about the various flags that can be used in the sorting (for regular, numeric, string and locale-based string handling) and the parameters to call for normal sorting, "natural" sorting, reverse key sorting and others. You can find specifics on these array sorting methods in the PHP manual.