The biggest slap in the face, for a teenager, is when they're getting disciplined from their mothers partner (Speaking from experience, and I resented her for letting him do it.. He took away the stuff I'd bought, with my own money).
Assuming, it's your normal situation.
That's a big no no in my book. Only in extreme circumstances, such as a genuine fear of harm or addiction, etc. would warrant that.
OP, I think you may do well with explaining to your daughter
why you're concerned about social networking, etc. She's probably still too young to understand the damages and in reality, pointlessness of the website but don't make the mistake of thinking you always know best even if you do. Teenagers resent that.
It would be wise also to remember that it is much harder these days for teenagers et al. to socialise outside like anyone pre-90s did when they were younger. Even as a teenager myself, despite wanting to do something as simple as kick-around in the park, it was nigh on impossible to motivate your friends to do so given the logistics involved or the fact they had the latest game's console or an addiction to an MMOG or FPS online. In my eyes, Facebook is simply the latest shift in socialising for younger generations. Their friends are all doing it during their formative years, so there's a huge pressure for them to do the same, whereas we as adults can see the website for what it
really should be: a tool to remain in contact. Not a tool to socialise through. There is nothing more irritating than sitting down a pub these days and having friends message eachother via their phones in facebook whilst they're sat in the same room, or even if they discuss the website. Likewise, wherever you go now you see bands of idiots taking photographs at every opportunity with the sole intention of posting them on Facebook to appear more social and happy than everyone else.
When I was 17, MySpace was fashionable. I eventually saw it for what it was: a breeding ground for social anxiety. Anyone born pre-80s probably (I can't say with authority though, as it may simply have manifested itself elsewhere) probably isn't fully aware of the social anxiety that social networking can cause a youngster; it constantly makes them feel second-best and in competition. For this reason alone, I think the OP is right to take action. However, you must remember a teenager is still a teenager and won't adopt a more mature perspective until they're ready to do so. Indeed, many 'adults' are just like these teenagers, except they have the freedom to not be pestered, nor would I even go as far as to suggest they know any better. Maturity can come at any age and it's only when the individual realises that Facebook isn't really worth worrying about to the point of obsession. By all means, keep contact, but don't treat it like a compulisve disorder.