Back when I started work, orkut was the rage. I spent a lot of time on orkut. A lot of time. It seemed like the right filler for days full of intermittent work. When you let the machine compile a huge jar file, there really isn't much you can do when the machine is compiling. Orkut filled this gap very well. Given the competitive nature of what I and my close friends were accustomed to, there was competition on orkut too: number of friends, number of scraps, fans etc. I know of people who came very close to screwing up academics (and hence life in a myopic sense) due to orkut. Orkut became a common noun, orkuting became a verb and an acceptable activity.
Orkut slowly gave way to facebook. There were a few other portals (which've been relegated to also rans - Friendster, Hi5, etc.) I was lucky to get early access to facebook thanks to being in a college that was covered by facebook. But I really didn't revel in facebook as much as I did on orkut. I found that it pushed people to be more phony than necessary.
The major difference between your orkut profile and your facebook profile was that the orkut relied on 'pull' in order to get recognition whereas facebook relied more on 'push' for recognition. It was a result of the basic design of the user homepage. Once logged in, Orkut opened to a page with your profile, your friends list and imminent birthdays of your friends. Facebook, on logging on, threw at you updates from what your friends were doing, saying and sharing.
This difference was stark. It meant that one would require different mindsets to navigate the two portals (soon they would become social networking sites) Facebook gave greater returns on pushy-ness, boldness and to an extant blatant self promotion. This came at a time when there was a mindset change in how people perceived the web.
This was around the time when Web 2.0 became a famous concept: when user generated content became the driver of the internet. Facebook fit better than orkut in the web 2.0. Also, let me not take anything away from facebook in terms of user interface, user experience and add-ons.
Close to the heels of facebook was twitter - a brilliant avenue to express, be-heard and self promote in the simplest of fashions. Twitter started a parallel network of connected people in a way nobody could imagine.
I heard of web 2.0 only after it became a huge talking point. Though I was on facebook, I had barely heard of twitter. When you have enough happening in real life, you rarely do look to the internet for excitement. It might have been a paucity of time which resulted in me not spending enough time or putting in enough effort on web 2.0.
I started using twitter regularly a month or so ago. Since then, I have been amazed by it. The design of the entire system is beautiful (I haven't figured it out fully yet) Between facebook and twitter, my vote surely is for twitter. It is smarter, quicker, adds greater value and doesn't damage once's personality as much. There are some simply outstanding people who make twitter what it is. It is almost like a large connected family out there which keeps the place abuzz.
But I have found that getting into the family is impossible (at least I haven't figured it out) And knowing social networks, being a male, out of college, with very few active friends on the network, the odds are stacked against me. Looking back, I feel that I missed the web 2.0 bus. I should have started being active on twitter long ago. But here I am, still searching, still trying to find my feet.