OK, I’ve neglected adding info on this site for a while. Was invited to Orkut a month or so ago, built my profile, and don’t use it that much. Orkut is in beta, and is the product or the folks at Google. The site is purely personal networking (friends) and the layout and capabilities are fairly basic. Probably the most useful function is the ability to click on your network and see the images of each of your friends, and by clicking on their image, you can then see everyone in their network (including yourself). You can keep clicking down through profile after profile.
Personally, I don’t find any value in this capability. You have no idea how subsequent selections are related to others in your network, or in how any of these people might be useful to add to your network. However, as with most purely social networking sites (non-business), you have the freedom to approach anyone about anything, and stike up a conversation whenever.
As far as categories, members have the ability to start any number of groups, and subscribe to any group. Most groups have many members, but not much conversation happening. That’s probably because there is so much overlap between groups, and no real way to tie them together. So instead of searching for a specific topic, its clear people are just creating a new topic. Orkut is Google’s obvious attempt to jump on the SN bandwagon, but overall there is not much there.