Etienne Kneuss has posted about some updates to the data structures functionality in the Standard PHP Library (SPL), specifically some new additions.
There finally is documentation for SplDoublyLinkedList, SplStack and SplQueue and some "new" classes: SplHeap (abstract), SplMaxHeap, SplMinHeap and SplPriorityQueue, documentation of those classes is in progress.
An example of the new functionality (for SplPriorityQueue) is included in the post showing the insertion of a value into a pre-existing array (without having to slice or splice!).