Although only Internet Explorer offers support for P3P, it is certainly a good idea to look into it and offer a plugin that generates P3P HTTP/HTML headers and the p3p XML file.

OASIS and IETF also offer different schemes in that regard and having support for those is certainly a good idea.

We need to see whether it is possible to offer privacy information that explain that a 3^rd party is keeping the data (i.e. m2osw.com) concerning things such as IP address, and Cookies, whereas site owners can generally only see more human data.

Technical Reference: Platform for Privacy Preferences (P3P) Project

Important Reference: Data Protection Directive (Europe)