Although Google has done an excellent job in the realm of scrapbooks, Orkut albums and friend updates (note: I'm still waiting on my Twitter/Jaiku hookup for Orkut status), they have yet to realize the full potential of their Orkut forums by not providing a way for users to subscribe to their favorite communities (a common mistake I am seeing across many social networks--especially the big ones).
While geeks may be able to get around this via Orkut Feeds (note: see the review over here), non-geeks may not be as motivated to engage their friends, foes and family on an Orkut community forum (as it is hard for you to know when someone responds back to you).
Instead of outsourcing subscriptions to the realm of geeks, Google should instead hook up with FeedBurner (which Google bought last year) and allow everyone to subscribe to their favorite forum thread (key word is thread, not the the entire forum) via email.
In order to keep the spam down, Google could only enable email subscriptions in moderated Orkut forums, as well as allow users to decide how frequently they want to receive updates (example: once a day, immediately or a general summary--similar to what they have in Google Groups).
This would benefit everyone as users would receive an email if someone responded to a thread, and Google would have a lot more active forums online (which would benefit their advertisers).
Note: While Google could always include RSS feeds within forums (something other users are asking for), RSS has yet to go mainstream (at least in America).