Maxime_Paquin, it is possible to get the embed code to insert any synth on another web page by using the first of the four icons near the lower right corner of any synth. Perhaps you just mean a 'share on facebook' icon?
The last time I tried to embed synths on a Windows Live profile or space or in Facebook, they rejected it on account of the iframe that it sits in, I believe. I, too, am eager to see this resolved.
As to tagging people in our synths, I would love it if the People Tags from the face detection in the latest version of Windows Live Photo Gallery were honored in synths. Since we tag people in photos using our Windows Live Contact List, a large percentage of the people tagged will have their own Windows Live ID. Also, since one must sign in to Photosynth using a Windows Live ID, it would only take an update to the Privacy Statement to show us what synths we appear in. This could be done in a private way if privacy issues are a concern.