The actual cookie law is so ambiguous that no company can properly adhere to the ‘law’ without severely damaging or hindering their site(s). Look at the UK Government; their sites are not yet compliant.

My advice is to wait for further clarification before coding in explicit ‘opt-in’ policies for ALL cookies. Whilst it’s nice to be compliant, it’s also nice to be compliant to a workable ‘law’. Virtually every site falls foul of this law. They’d have to sue everyone, and who are ‘they’ exactly? This is the net neutral, country agnostic internet. Good luck.