People are buzzing more and more about the need to understand “social network migration,” particularly in the wake of what looks like a  mini-exodus of sorts from MySpace to Facebook. “Migration” is an interesting metaphor. It situates one site as Homeland, and implies that groups of people then pack up and move to a new land. Of course, “migration” also has a bit of a seasonal quality, implying that when the winds shift, people will up and leave once again.

I’m sure that’s happening, but there’s another equally important phenomenon we shouldn’t overlook: multiple residency. People are building digital abodes in more than one site. Rather than moving from one site to another, many people are hanging out in several of these spaces at once – something that is getting easier and easier with applications and widgets that import and export information across them.

I recently surveyed approximately 600 users of Last.fm. One question I asked was whether they used “any other social network sites such as MySpace or Facebook.” Two thirds of them said yes.

When asked whether a random friendship they had on Last.fm was also a friend on another site, half of those who used other social network sites said yes. In other words, a third of friendship pairs on Last.fm are also “friends” on at least one other social network site.

Two of my graduate students and I are in the process of making sense of the answers to the open-ended question of how they would compare their Last.fm friendships to those on other sites, but I can tell you that they are all over the place. Some speak of Last.fm friendships as being more important and exclusive because they are based on shared music. Some speak of Last.fm friendships as more trivial and irrelevant because they are based only on music.

In my own case, there is a subset of my Last.fm friends who are Facebook friends. I have more Facebook friends, but I will add almost anyone who seems to have a decent reason to want to be my friend on Last.fm, but I’ll only friend people I already know or know that I want to know on Facebook.  Some Last.fm and Facebook friends are LinkedIn and Flickr contacts. I’m not sure if anyone connects with me in all 4 of those sites, I don’t think so.

Each site manages different dimensions of our relationships, and I don’t particularly want it all fused into a single site, especially if that single site is under corporate ownership. By diversifying my social existence online I can foreground some relational qualities in each site, but I can also spread the risk of dependence on dubiously trustworthy longterm providers.

Thinking in terms of “migration” makes little sense if one wants to understand how people make choices amongst which sites they use for which purposes.