Facebook vs Email
The vortex of Facebook junkies around me have sucked me into the Facebook abyss as well. My wife's family started it, but now a lot of people I know are using it. I just found out that in Ottawa, approximately 1 in 10 people is using Facebook.
Email has been becoming increasingly useless. So have blog comments. Almost any form of open communication is being co-opted by spammers. Even private messages in World of Warcraft have been taken over; it's a rare session now when I log in and don't have gold farmer spam waiting for me in my in-game inbox.
Whitelist email works, but maintaining your list is a pain. People move, change jobs, change ISPs, and get new email addresses. One of the reasons Facebook works so well is that you're not whitelisting an email address or URL or some technical way of contacting someone; you're whitelisting a person.
That person maintains their own information, and Facebook maintains the relationship between you and them.
I find the communication I have with friends on Facebook is generally easier to initiate and more engaging than most email, because it's surrounded in context. If someone in my family posts a photo, they're not just sending me pictures; they're posting photos and Facebook is telling me (via my home page) that they've done it; I can look at them if I like, and post comments on them. A lot of ad-hoc conversations happen around photos this way.
There's a lot of the eBay effect in Facebook: You really only want to belong to one social networking site, and that's the one with most of your friends on it. Facebook has achieved critical mass, and so will likely dominate for the next few years.
What I want in Facebook is a way to create circles of friends and restrict access based on that. For example, people I might become friends with someone through the blog, but does that mean I want them to see my entire friends list? Probably not. But with Facebook, it's all or nothing.