I have an iPhone 3GS. Works fine for me and I'd like to keep it as long as possible, but I realize it's getting a little long in the tooth compared to the latest iPhone and upcoming iPhone 5. I'm wondering what will happen when it gets too old to support future iOS upgrades? When I plug it into my computer and go to iTunes will it no longer tell me there's an upgrade available? And what about the apps? Are they frozen in time? Are they still able to function?