I connected my WP7 with my Live account, in order to Sync the contacts. By the way these contacts comes from a GMail account, but I don't think it is strictly a problem. Apparently none of the imported contact are visible, the only way to have these sync properly is to "touch" by modifyng/adding something in the contact. Is there some way to solve this issue ?
I found a workaround, maybe not the best one,but worked for me: I exported the contacts from GMail to CSV in outlook format, then I imported that file in Live. After that all works like a charm.