Instantbird is a new instant messaging application that merges two powerful open source projects: XULRunner, the stand-alone version of Firefox browsing engine; and libpurple, the library that gives Pidgin its ability to connect to most of the existing instant messaging networks.

The first development release, 0.1, provides the very basic functionality of what we have come to expect from an instant messaging application. On first run, an account wizard pops up to add your first IM account from any of the 16 networks libpurple supports. Enter your username, password and you are good to go.

I was able to exchange a couple of messages with my wife over Yahoo’s network before it crashed. And it stayed crashing until I deleted my profile. The chat window has a text area to enter the message and an area where messages are displayed. The lack of preferences, save IM accounts parameters, quickly confirms it is at a very early development stage.

So what’s the purpose of Instantbird? After all Pidgin already is an open source multiplatform IM client. I think there are a couple of advantages Florian Quèze and Quentin Castiers, the Instantbird developers may be after: extensibility and web awareness.

The roadmap lists some limited extensibility for next version, 0.2: localizable, smiley and sound themes and more interestingly, the ability to add networks through extensions.

But as they develop a strong and flexible program interface, it could extend to any area imaginable, like the Firefox or Songbird cases. Add to it XULRunner’s web handling muscle and it’s not too hard to envision an application that lets users reach friends wherever they are connected to and not just over IM networks.

So kudos to Quentin and Florian. Hope we will all see a solid and innovative IM client in a not so distant future.

Instantbird is available for Windows, Linux and Mac OS X.

Update: Learn more on this interview with Quentin and Florian, Instantbird developers.