I have an iPhone 3GS and I noticed that when you have the app volume all the way down, not ringer volume, when you lock your iPhone, it makes this muffled, different lock noise. At first I was thinking I just had my finger over the speaker hole cause I usually do, but it wasn't because of that. I wonder if it is 3.0 related because that never happened on my 2G. It really isn't even a big deal, but just something about that noise makes me feel like I am not leaving my iPhone the right way, so I have to open up an app and turn the volume up or go into options. Anyone else have the same problem?