Disclaimer: This does not constitute legal advice, consult a solicitor or contact the ico if in doubt.
In case you didn’t know already, the EU cookie laws came in May 2011, but the ico have only decided to enforce this from May 2012.
Most of the big companies are complying. In a nutshell, you’re meant to get permission to put cookies on a visitors computer, unless it is used for the operation of the website, such as a shopping basket cookie.
You can get away with implied consent, according to the ico, but I’d read the guide carefully, as I doubt you can get away with implied consent for behavioural advertising.
If you aren’t yet compliant, I recommend you get it sorted asap.
This post was written on my mobile phone, so please excuse any spelling mistakes!