The Google Voice app does badges differently than most. The badges for most apps will tell you how many notifications you've received since last opening the app. Google Voice will tell you how many unread items are in your inbox. So even immediately after closing the app, it can still have a badge (much like Mail). However, ever since iOS 5, it doesn't work as well as it used to. It will still go up if you receive a new message without having to open the app, but it used to also go down if you responded to an unread message from, say, your computer. But now the badge number won't update and go down unless you actually open the app. Since this coincided exactly with the release of iOS 5, I'm guessing it was an iOS change, and not a Google change. Does anyone have any idea why this would be? It's way less useful this way.