If you’re one of the millions who downloaded and used the notorious I Am T-Pain iPhone app then hit your upgrade buttons today, as you’ve got an upgrade you just might like. The latest version is wrapped up in lovely iOS4 improvements, but also offers a fab feature for the iPhone 4 — you can use that front-facing video camera to film yourself singing along to something or other while using the Auto-tune feature. Then, assuming friends, family or concerned neighbors haven’t made some kind of intervention to save you from future workplace embarrassment. You can even send those clips right…