Social networking sites are growing up and becoming much more than glorified address books, says Bill Thompson.
About a year ago I asked my daughter, who was 15 at the time, if she would "ADD" me as a friend on MySpace so I could comment on her profile and be part of her online social network.
She refused point blank.
Not because she wanted to keep things secret, but because it would be unutterably naff to have your dad as a MySpace friend.
Recognising that she was right, I didn't push it.
She knows how to look after herself online - she's a member of the Childnet International children's' panel and helps write the guidance for other young people.
But yesterday she added me as a friend on Facebook, where she now has a profile too. Not only that, she has admitted in public that she is my daughter.
A brave step indeed.
In fact, I'm less concerned with her privacy now than I am with my own.
She's 16 and can look after herself, but now she has access to my online friendship network. Not only will she be able to see who I'm hanging out with, she'll also be able to send them all messages.
This is one of the big problems with Facebook, Bebo, MySpace and the other social network sites.
They bring the many different groups we all belong to into one online space, creating a "social soup" that encourages intermingling when most of us work hard to keep our friends, family and colleagues just a little bit separate, negotiating the boundaries with more or less skill.
The tools used to manage privacy and sharing online remain crude and inflexible compared with the nuanced way we handle real-life social networks, and we are going to have to learn to deal with the new modes of social engagement that result.
Although Lili is now on Facebook, she is adamant that she'll stay on MySpace too, a view that has forced me to revise the model of social network progression I've put forward in the past.
I used to think that young people would start off in the controlled environment of Penguin World or Habbo Hotel, move to the adolescent chaos that is MySpace and then mature into confident Facebook users. But I suspect it will be a lot less clear cut.
For one thing, you can't pimp your Facebook profile with garish colours, unreadable fonts and appalling backgrounds. And while Facebook offers a "wall" to write comments on, it lacks the directness of a MySpace profile.
Whether or not she abandons MySpace, I do think that Facebook will become more important to her simply because it is rapidly becoming more than just a social network site.
Its support for third-party applications and services is turning it into a platform for all other forms of online social activity, from talking about movies via the Flixster application to asking friends questions or "superpoking" them.
Facebook may well become the single point of contact with one's online networks, wherever they may be hosted.
I rarely visit Twitter, the site that lets you send short updates about what you're up to, because it's easier to post from within Facebook. And as this trend develops, more and more of us will spend more and more time on Facebook instead of elsewhere.
Once someone builds "MySpaceBook", an application that lets you run your MySpace profile from within Facebook, the game will be over.
Of course, we need to temper our enthusiasm for this connected world.
Google was recently criticised by Privacy International over its cavalier "trust us, we're not evil" attitude to personal privacy and user information, and we need to make sure that we are not asking the same questions about Facebook in two years' time.
Yet privacy concerns do not bother most of Google's hundreds of millions of users, and they are unlikely to stop Facebook's rapid adoption, so it is worth speculating about where social network sites will go next.
One thing that may change significantly is the way we interact with the services. At the moment, Facebook and MySpace are page-oriented and text-heavy, but alternatives seem to be emerging.
Like many other technology watchers, I've been captivated recently by a preview release of a new program called Photosynth, developed at Microsoft Live labs.
This astonishing piece of technology gives the lie to the tale that Microsoft is unable to innovate effectively and could change the way we think about live online.
Photosynth takes a large number of photos of a place or an object, analyses them for similarities, and then stitches them together into a three-dimensional space that allows you to move from photo to photo by clicking, scrolling and panning around in a way which is completely captivating.
It is the future of user interaction, the way we will manage to take the flat 2D web that we currently experience and turn it into a virtual world.
Photosynth works with pictures, but pictures are just data and there is no reason I can see why it could not also work with user profiles, web pages, maps or any other form of semi-structured data.
I could navigate my social network as easily as I navigate the collection of photos of the Piazza San Marco in Venice that is provided as one of the demonstrations, or move from web page to web page following a breaking news story.
With Facebook as the open social network platform, Google offering search, e-mail and applications, and Photosynth stitching it all together into one graphical 3D space that we navigate with a mouse or a Nintendo Wii-like controller, we are moving closer to the model of cyberspace described by William Gibson in his 1984 novel Neuromancer.
Gibson imagined an online world in which large corporations defined rigid hierarchical structures of data like the "stepped scarlet pyramid of the Eastern Seaboard Fission Authority".
By contrast, we could have billions of Flickr photos and Facebook profiles stitched together into an ever-changing quilt, but the end result would be the "graphic representation of data abstracted from banks of every computer in the human system" that he described.
We may be watching on screens instead of having a direct neural input allowing us to "jack in" to the matrix, but it will still be a lot more fun than today's flat web.