I certainly won't be applying for one. If my existing driver's license, passport, and birth certificate aren't good enough for anybody, then too bad.
Maybe I'm getting too cynical, but I see this scheme as an attempt to soften people up into accepting the idea of ID cards. I'm sure the government must believe that if people will accept a government-backed, but privately run and voluntary system of ID cards, then they'll be a much softer touch for when they decide to make government-issued ID compulsory. I won't be applying for one of those cards either.