More Convergence: How Twitter (as an open protocol, ideally) could (and maybe will) replace IM and all web commenting and make them both better
I've been messing with different Twitter clients. My favorite desktop client is still TwitterGadget, because it's so lightweight and is fairly keyboard friendly (though it certainly has room to improve on this front). It's actually a Gmail gadget, but I use it as a Prism application. Tweetdeck and Twhirl seem to be the most popular desktop clients, but they're not that responsive for me maybe because they're Adobe Air applications. I'm sure they're great for heavy Twitter users, but for the functionality that Twitter provides for me at this point, all I really want is something simple and lightweight.
SimplyTweet is still my favorite iPod Touch client, and I wish there was a desktop version, frankly. The feature list is really great, and includes: Instapaper support(!); a "View Conversation" button for each tweet, which is a bit buggy but is a really cool idea; grouping, in the form of "Saved Views" that filters by contact and "Saved Searches" which filters by keyword.
Really, I think those are about all the features you need in a desktop client to replace IM and make Twitter more robust and give it a more immediate, IRC-like conversational feel. With #hashtags and direct messages, Twitter already has most of the functionality. The Adobe Air applications that I mentioned earlier are almost there with their columns, but I imagine the experience more like my hands-down favorite IM client, Digsby. Each window/tab would represent either a contact (a two-way conversation); a user-defined group (e.g. "Real Friends" or "Apps" (which are actually two of my saved views in SimplyTweet)); a keyword search (firehose of what people are saying about a given subject); or a #hashtag (make-shift chatroom on a given subject, or, really, not (on a given subject)). The client could use the direct messaging functionality to make two-way or group conversations private.
For a two-way chat, the tab/window would simply be a filter for that contact's @replies, and would transparently append the appropriate @reply to each message sent from the tab/window. Groups and searches would just be normal filtered views. #Hashtag chatrooms, then, would just be a filtered view of the #hashtag that would append the #hashtag onto outgoing messages. I think how private chats would work is with some sort of obfuscated #hashtag and the client would transparently send direct messages to all the parties involved.
Since I imagine #hashtags would have to become arbitrarily long, Twitter would probably have to get rid of the artificial 140 character limit, which I think is pretty stupid and arbitrary (does anyone really use the text message interface to Twitter?) anyway.
I think something like this would make Twitter much more engaging. Twitter isn't as amenable to long conversations as it is to unprompted unidirectional musings, which are fine, but aren't suitable to everyone (i.e. me). It also opens up all of the conversation that happens in private right now over IM to the public. Not that all conversation should be public, but there's no real reason for a lot of it to be private, and if it's in the public, it can potentially engage and connect many people who might otherwise be unaware of each other.
Also, Twitter comments becoming a standard would be cool (I'm looking into implementing it here[^1]). This would expose stuff about what you're reading and commenting on to your Twitter stream, creating a conversation space on Twitter about a post, and also provides an element of persistent online identity that I've written about before. I can even imagine some sort of trackback system implementation that aggregates commenting on a subject across websites to make one giant conversation about a subject as opposed to a particular blog post or whatever.
Twitter's simplicity allows it to be extremely flexible, which is why it's already being used in so many different ways, and what gives it so much potential. And also why it should become an open protocol, like email.
Aside: I'm wondering if anyone uses the "Favorites" functionality of twitter. Apparently you can mark individual tweets. I'm not sure how that's useful.
[^1]: Update: I just realized Disqus has integrated with Twitter, which is close, but not all there.