Yeah the progress bar usually nearly instantly goes all the way to the end (100%) and then just sits there for like 30 seconds or so.
Kind of annoying. The phone is also sluggish during this time in certain areas, such as the app store. Which is even more annoying because if you are downloading and installing apps, chances are you are still browsing the store for more goodies.
Nature of the beast I guess. If they can't speed it up, I would personally at least like to see a status bar that is accurate, that is, it doesn't say 100% until it's DONE.