I'm generally not a huge fan of photo tagging — mostly because there's always the potential of being tagged in an unflattering photo (and there's always the pesky gray line of whether or not to tag a date). Luckily, Flickr feels my pain: you can choose which members are allowed to add you in photos, and who is allowed to tag people in photos you've shared. Plus, if you remove a tag of yourself from a photo, only you can re-tag the photo with your name.
The Flickr FAQ page contains more details and specifics. I'm already getting tag updates from friends in my Flickr feed — it's a great way to discover new photos of people you know.