As well as a clear option, PhoneDevil.com is offering new screen protectors for iPhone 3Gs and iPhone 3GSes that in one instance shields your phone's screen from prying eyes and in the other, doubles as a mirror.
The Magic Screen mirror edition film claims to protect your phone's screen from scratches and then "transforms the screen into a perfect mirror while not in use".
The Magic Screen privacy edition uses 3M "privacy material" designed to allow vertical viewing of the phone screen, but not from-the-side viewing, so will protect your phone privacy from nosy parkers on the bus or tube.
However, vertical viewing is enabled (when the phone is held in portrait mode), is so that when the phone is used in landscape mode for games, the screen can still be seen while tilting the phone.
The film is said to be easy to apply and does not need cutting. The claim is that is can easily be removed (leaving no marks) and re-applied.
The clear version is £4.97, mirror edition £6.97 and the privacy edition costs £9.97, all available now from PhoneDevil.com.