While the iPhone owners at Gizmodo seem unable to locate the white iPhone 4s on the revamped Apple Store app, you can at least reserve products for purchase, engrave stuff, and schedule Genius Bar appointments.
Version 1.1 of the app builds on the original (and basic) app, with the aforementioned services plus you can now request your item to be gift-wrapped. Stores can be located on the map and if you make appointments they can now be added to iCal, which seems like a real no-brainer.
It's still free, and just needs iOS 3.0 or later. [iTunes via AppShopper]