Yesterday afternoon I had a meeting with some guys from microchip Italy R&D department. For those who are interesteed of power LED products (like emergency luminaires), engineers there made a good design using a dsPIC (28 pins, price <= 1 euro) that controls power LEDs with a PWM at 500KHz. They also told me that a new smaller design will be ready in some days.
As they told me schematics, pcbs and source code is free for everyone. Also they sell their design as a reference.
I tell you this as an information.