I've determined independently that a IRC server fills a sweet spot in the collaborative toolset. A basic IM system isn't good enough because it doesn't have channels, it doesn't give you a shared history. Email is heavy and induces people to spend too much time per message.
Sometimes it's good to have a light/noisy feed, and IRC is just fine for that job.
Eh, that's pretty much what BNCs or tmux/screen is for. The number of hours that I haven't been connected to IRC in the past 10 years is probably low-double digits. (I'm on several networks so a network outage won't knock me off IRC entirely.)
Plus with IRC you have the assurance that it will never go away. Worse case scenario is you just write your own server and do it yourself. There is no RFC for skype though.
We use a IRC bouncer for this; It works really well to preserve history, and let me get messages when I'm offline.
when I disconnect, it automatically sets me /away, and renames my nick to e1ven_zz to make it clear to the rest of the team I'm away.. When I log back in, it renames me back to e1ven, and streams everything I missed.
Checkout HipChat. Like IRC and has a desktop and web client. They also have API which you can use to post messages to channels from external sources. We have our Capistrano/Ant scripts post their status to our "Deployment" channel. Currently working on a bot that hooks into Jenkins so we can build via our "development" channel.
We use Hipchat at work at the moment and while I like it overall there are some issues that they need to address.
The Air app for desktop can sometimes have performance issues for no particular reason. They're about to release a native OS X app though so that should solve this for a large amount of users.
The android application in woeful. It consistently logs me out and forgets my password which means that it's totally unusable for out of office notifications from people. I've had to rely more on their email notifications for unread personal messages than their Android app. It's a real shame because I could see myself getting a lot more use out of Hipchat if it worked well enough.
The web client is a bit "special" though - after a day or two of running it with 4+ channels open the history will build up and jquery functions will start freezing the interaction. Flash/AIR client is much better, but... it's Flash/AIR (copy/paste issues, different set of fonts, message notifications not clear).
The best way to access hipchat that I've seen so far was just a jabber client - xmpp seems to be the backend of their service.
On the mac, at least, I've found the AIR client is really, really good. I haven't really run into any of the issues you mentioned and have been using it daily for several months.
And my coworkers really love the web client. And some use xmpp. Many of us regularly use the iOS app. I guess that's one of the strength's of hipchat, the variety of access methods that all feel basically first-class. (and one person on our team even uses the SMS integration.)
I don't agree that email is heavy at all. I see nothing here that couldn't be accomplished with email and/or a wiki. Sharing links over irc makes little sense, links belong on a wiki so they can be searched for and edited etc etc.
You would be hard pressed to find anybody using IRC who doesn't also use email and wikis. Once you add IRC to your toolbelt, those things, as if by magic, stop appearing to be the best tool for every job. Actually, it works that way with most tools I find.
But that's the appeal of IRC, the protocol is simple and it's easy to write tools that plugin and work with the stream.
In the case of links, a little bit of Python and the phenny framework let me write a bot that scraped links and post them to a private Twitter feed. That's a lot more flexible than a wiki for my purposes.
Sometimes it's good to have a light/noisy feed, and IRC is just fine for that job.