A community without communication is a dead community and friendship is more than just a wall of faces. Connections between people are born out of interactions between them and strength of connections are primarily based on the amount and frequency of interactions.
So it is communication that binds people and communities together yet there is little of that going on in Orkut. Yes, there is the message feature but it's works more like radio and discourages interaction. Communities have topics, but topics are little rooms one must make effort to enter and compartmentalized conversations within a group setting do not encourage others to join in uninvited.
To get around these problems. I think permachats should be created centered around individuals and communities. A permachat is like IRC except conversations takes place over much longer period, days even. Visibility of permachat should be limited to friends or friends of friends only. Amount is determined by rate of actvity. To promote interaction and to encourage the sense of conversation, sense of time is removed, leaving only faces and names next to each entry. Amount of activity within past 24 hours should be displayed in the 'view network' and 'my communities' pages using color hints (i.e. red for hot).
Permachat allows people who know me to communicate with me as well as others who know me. This in turns allows them to become friends over time instead of using more explicit introduction based social networking. It also allows interaction without spammy messages invading private spaces and deteriorating sense of friendship.
For communities, permachat serves as the single thread that binds the community. Topics is too focus-oriented to serve this function. Permachat allows casual conversations, encourages interaction, and informs every member with minimal effort. And, most importantly, permachat allows new friendship to be born out these intereactions among community members just as conversations among friends of an individual helps them form new friendships.
A working example of permachat is #joiito. #joiito IRC channel not only binds the friendship network centered around Joi, but also builds a community in itself as people get to know each other. Topics come and go just as Joi comes and goes, but the conversation rolls on and weaves its social magic around everyone. I think Orkut use a bit of that magic.