What do you guys think of these proposed features?

The rules have evolved over time.

When I first started using Twitter, the main purpose was just to communicate with my wife and kids, specifically for a spring break when they headed to Florida and I stayed north to work on academic stuff. That expanded quickly to a small set of 20 or so people, which included both friends and fellow grad students and a couple of celebrities (Steven Wright and Jim Gaffigan, neither of whom make any use of the medium).

As more people in our grad program started using Twitter, I became interested in using it for some research. My focus then became identifying Informatics students, faculty and alums, and following anyone who lived in my region. This got me up to about 100. My geographic rules included nearby towns, because few people were using Twitter at the time.

As it became more successful, I created a second account for my academic tracking and started pruning some of the locals and regional people I followed to increase relevance. I went to a few events where more people wound up following me than I returned, mainly because I wanted to focus just on people in town. I started following just a few people outside of the academic-geographic range if they were of interest, but many of those were not reciprocated (Lee LeFever et al). There was also an increase in Twitter application accounts and a few blogs (Comix Mix, The Onion) that I followed. My network was approaching 300 by this time, far more than I ever anticipated following.

I continue to follow all new Informatics students indiscriminately and have added some locals who have joined Twitter. For a brief time, I followed sets of fictional characters on Twitter (Battlestar Gallactica, Buffy, Laura Ingalls Wilder, etc) but wound up pruning them back because the fiction wasn't as intriguing as real people.

There is another Startup Weekend event coming up next month, this time in Indy. I am certain that the people I meet there will be followed, expanding my network again. I've also got a book due out in the Spring, so I anticipate another spurt of growth around that.

In a nutshell, every time I say there is no way I am going to follow more people, my network grows to a new size. Also true: I only do so when I am ready to grow. So some of the people on my list never would have been followed last year. It also may have been intimidating to follow everyone in Informatics, say, if I wasn't there when that Twitter community was small and manageable. ( Delete or Edit)

1) I wouldn't separate "relationship building" from "staying in touch" To me, that is all part of the cycle of disconnection and reconnection. The other two usage cases you mention are specific tasks that benefit from strong relationships. Collaboration on Twitter is not a deep activity. Things are initiated there and reality checks done to poll progress throughout, but the work itself is done elsewhere.

2 & 3) I know there are people who crave the ability to separate subgroups of followers, even going to far as to create and manage multiple Twitter identities (one for local, one for professional). This really needs to be separated into to different aspects: publishing and organizing.

Identity management is not a part of Twitter for me, however. The ability to unfollow (or, with Twalala, even mute people for a while) is always there for people to use. I try to be true to myself, which means sometimes I am noisy and sometimes what I type interests mainly one group. I'm not interested in tweeting different things to different groups. In doing so, I'd think I might impose what I think certain people should know rather than just letting everyone else make up their own minds about any value a tweet might hold.

The second aspect is organization, and for that I am still waiting for some kind of directory management that allows me to tag, flag and search for people in my network in a meaningful way. The best way to search right now is actually to guess someone's Twitter handle (which I rarely see anymore, with use of Full Names in Twitterrific and the ability to click reply buttons). There is nothing that would allow me to track former people I follow, maybe with a note reminding me when/why I stopped. These kinds of things have nothing to do with the outward relationship or publication of content, but it is a way larger and larger networks can make sense. Maybe even something that connects them to other social network pages, like LinkedIn. ( Delete or Edit)