Bike Forums - Compact cranks -- problems??

I'm new to the world of compact cranks and trying to understand why campy is making a special front derailleur for their compact chorus and record cranks that have just been released. Is there a problem with shifting on compacts generally with standard derailleurs??? I'm looking to by an FSA carbon compact for a bike I'm building this month and will be running campy centaur or ultegra 9spd ... is there anything I should know about this before hand?? I can't imagine they could work too poorly, since no company that I know of (other than campy) makes a special front derailleur for a compact. Thanks for the help!