[kstenerud]

So does this mean that things such as "like" and "+1" buttons don't work unless you subvert the P3P protocol?

[spullara]

It means that they don't work unless the user enables tracking by third parties on first party websites.

[kstenerud]

So if someone goes to Mashable and clicks a "like" button, it won't work unless they specifically allow 3rd party tracking on Mashable? And then again on the WSJ, and again on Youtube? Or is it that they need to allow Facebook tracking once and then it works on all sites that have a "like" button?

If it's the former, then I'd say P3P is horribly broken and bypassing it for "like" buttons would be the only way to make things work.

And even if it's the latter, giving a site carte blanche tracking rights seems too coarse for comfort (unless you could grant permission ONLY for "like" buttons and nothing else).