Facebook made a few significant changes that became visible to most users starting last night.

• Restructured activity stream - you can now choose exactly who you want to see in your activity stream and what kinds of activity you want to see from them, as well as how much you want them to show up.
• Subscriptions - you can subscribe to people you're not friends with, so you can follow thought leaders like on on Twitter without having to actually have a mutual friendship. This also makes your stream more interesting.

I've been building open-source social networking software for the past four years, which has given me the unique opportunity to be involved in a wide variety of projects to build social networks and related tools. My experience has revealed a number of insights into the way that user interaction patterns are designed on websites that encourage a website's engagement and adoption to the point that it can grow organically from almost nothing – or, conversely, that doom a website to silent irrelevance in a distant corner of the web.

If you stay up-to-date with what's in vogue among the technology elite, you've probably heard about turntable.fm. If you haven't, let me tell you: it's a website where you listen to music with other people. And when I say with other people, I mean it looks like your avatar is standing in a club with other people listening to DJs up on a booth. You can rate the song as "Awesome" or "Lame," chat with other clubbers, and even DJ if there's a free spot. DJs get points for awesome songs that let them get new avatars. It's absurdly addicting. And so the tech world has been abuzz with praise that has typically failed to see the really important lessons here.