Instantbird chat covers a wide variety of platforms. AIM, MSN, Yahoo, ICQ, Google Talk, Twitter, Facebook, IRC, Gadu-Gadu, GroupWise, Myspace, Netsoul, QQ, Sametime, and XMPP are pretty much it.
Setting up one of your chat accounts is very simple and straightforward. The program itself is super simple to use with nice bubble style chat graphics. If you dont like those, its easily customizable with a few themes built in and several more available to download on the website. Speaking of which, there are plenty of add-ons for Instantbird. There is even a Live Journal chat protocol plugin. I see a plugin called "Unity-bird" which adds Unity integration to the app. The preferences options are in depth (unlike Empathy for example)
* Notes: The tray icon is UGLY in Ubuntu 11.10. I also dont see a way to show offline users. While not something I totally care about, its nice once in a while to see the entire list of friends, online or offline.
Is it available in the Ubuntu Software Center? Nope. You can download it from their website here:
Once you have downloaded the file, extract it. Then you should be able to double click the "instantbird" file in the new folder. If the program doesnt come up, right click the "instantbird" file, go into permissions tab and checkmark the "allow executing" option.
If you like the program, you can put the Instantbird folder wherever you like, and then make a launcher to the "instantbird' file.