I have an iPhone 4 too and would definitely recommend it. I know you can use Rhythmbox to sync music and videos to the device. Not sure about apps, but you can

I have an iPhone 4 too and would definitely recommend it. I know you can use Rhythmbox to sync music and videos to the device. Not sure about apps, but you can definitely just download apps on the device itself. Also, I hear iTunes runs fine in Wine, so that's also an option.