So I have a 3GS and I have iOS 4 installed. I was in the google app and I went to apps, then clicked gmail. It behaves as expected, where it will jump out of the google app and go into safari to open up the mobile gmail, but for a split second I see this. Now based off of this review, http://www.tipb.com/2010/06/14/ios-4-walkthrough/, it says that band is for VOIP to indicate that a call is in session or something. Maybe google already put some code in place and maybe, just maybe full google voice and latitude will be options for iOS 4.