For unknown reasons Google Browser Sync has been discontinued in Firefox 3 and for Firefox 2 users will be maintained till the end of the year. Mozilla's effort, Weave, has still a long way to go until reaching a production state. Luckily, the latest update of Foxmarks brings that feature online again. Those already using it, check it's options. The others can get it either from https://addons.mozilla.org or www.foxmarks.com
The PIN has to be manually typed/activated in each of the boxes/installs that runs Foxmarks. Else, on an old Foxmarks install even if Pass Sync has been activated on another box, only the default bookmark sync will occur.
For safer browsing, use OpenDNS nameservers 126.96.36.199 and 188.8.131.52