In the past 48 hours, I've had three very different conversations about social networking, touching on US and Asian variants like Myspace and Cyworld (in Korean or about Cyworld in English). In each case, my perspective was a little different than that of the people I was talking with, so maybe it's worth setting out.
A social networking environment (software, etc.) is necessary but not sufficient for success. Success depends upon communities. That's the reason Myspace is doing so well and Friendster has languished. As Anick Jesdanun points out,
...when its founders noticed heavy usage among musicians and fans, MySpace embraced that community with custom features... ultimately music is what made MySpace special.
Once communities had formed around bands, musicians and their fans, Myspace was off and running.
Of course the underlying social networking software must have competitive features, but I already run four instant messenger clients because the different communities I participate in happen to run on different platforms. It's the communities, not the platform that counts.
I've looked at (and joined) Myspace and Facebook, but they are both Internet centric, i.e. no mobile support. Not reading Korean, Chinese or Japanese, I haven't been able to join Cyworld. Luckily, at 3GSM, I ran into long time friends Kevin Chia and Michele Chan of Singapore who are operating an interesting Internet/ mobile community under the name 12wap (pronounced "want to wap"). I've just started exploring 12wap which lets you set up both WAP and Internet homepages. I haven't set up my home page, but you can see my photo on your mobile at wap address 16172850433.12wap.net :-)