I'd love to see this as well, I use it all the time in Ai and it's a time saver for sure. I've figured out that if you have two items and you want them centered to each other in the area of one of them, you need to align them to the left or right first (which ever one you want to keep in the position), deselect them, select them again and align them to the top or bottom of each other (again which ever one you want to keep in the position), deselect them, select them again and then align center on both. A really long process that should have taken 3 clicks at most. I hope this made sense. It's a really long way about getting the objects centered while keeping them in the space of the one you wanted to keep location for.