Are there any worthwhile alternatives to the official PS3 wireless keyboard?
Apart from the official PS3 wireless keyboard, every other keyboard I have investigated appears to lack full support for PS3 specific buttons (R1, R2, L1, L2, Triange, Circle, Square, Cross, Select, Start, PS).
The best of the bunch in my opinion is the Logitech DiNovo Mini keyboard. It isn't cheap but is beautifully made, has cool LEDs, great battery life and the keyboard/trackpad is excellent. Although not designed specifically for the PS3, it does have a PS3 switch that remaps some of the keys to be PS3 orientated. (i.e. Cross = Enter, Circle = Esc, Triangle = Fn + OK, PS button = MS logo etc).
Once the keyboard has been paired with the PS3 it works instantly. If I want to type something, I flip up the lid of the DiNovo and just start typing.
Again not specifically for the PS3, but I am using the CHINFAI Silicone wireless keyboard.
A little bit hard to type upon, but after you get used to its wobbly keys, its main feature is that it can be rolled up and stored inside your travel bag if you carry your PS3 to your friends and need your tools with you.