I want to connect iphone to a printer via bluetooth, but I don\'t find any class about bluetooth in iPhone 3.0 SDK. Do I need to join \"Made for iPod and Works with iPhone L
You might want to check into the GameKit. I just used it to connect two iPod's via bluetooth. Apple has done all the hard work and with just a few lines of code, you can have the iPod searching for bluetooth devices. If you do your own Wifi networking, you can even make the iPod/ iPhone search for the printer using either bluetooth or wifi relatively easy.
"and incorporate an Apple-specific chip"
Rubbish! Bluetooth is Bluetooth is Bluetooth. What is needed is for proper Bluetooth support on the iPhone.
Even if you join the MFi/WWi developer program, it's impossible to connect your iPhone to an arbitrary printer. The printer would need to built specifically for iPhone compatibility and incorporate an Apple-specific chip. The program is intended for device manufacturers to build iPod/iPhone specific devices, not for independent developers or device manufacturers with existing bluetooth products.