I used to be a Google Reader&#x2F;Google Buzz addict. And was interacting with a very living community through those tools.
I now use twitter as my exclusive medium for both mainstream and &quot;niche&quot; news.
I appreciate the wide availability of content, but still think they are much too conservative with their user experience. 
The inability to browse tweets by topic is sometimes a pain.
The inability to connect with the right people and build a discussion about topics you discover and find interesting.
Basically twitter should have a chatroom. And propose you conversations about (your) trending topics.