The moment I learned Mountain Lion would have a Notification Center, I thought it would make sense to offer to receive notifications from other devices on the same iCloud account. For example, you could choose to get "Messages" notifications from your iPhone synced to your Mac, so that when you get a text message / iMessage it displays on your Mac too. Would be very useful if your iPhone is not in your pocket. It would work well with the Phone app too for missed calls / new voicemail and some mobile-only games that send you notifications while you're not playing (like Draw Something), alarms from the Clock app, new Newsstand issue availability, etc. Is such a feature planned or in current developer builds? If not, is that something you would like to see? I certainly would!