I am making a library called "IrrBazAR", that convert "any image" you want as your markers.
Here is the demo video of the first version of IrrBazAR.
http://www.youtube.com/watch?v=MnX99sJsFa0
Irrlicht integrated with BazAR (augmented reality tool)
I had my hopes up for a second but it seems to be GPL just like ARToolKit. They could atleast use the LGPL or something. <---The FSF would frown on this sentence. Anyway, it's interesting that you can use ANY image as your marker. Could lead to interesting possibilities like face detection, etc. Good work.
ShadowMapping for Irrlicht!: Get it here
Need help? Come on the IRC!: #irrlicht on irc://irc.freenode.net
Need help? Come on the IRC!: #irrlicht on irc://irc.freenode.net
Just make the part of your project that uses the GPL a seperate program that communicates to your program through tcp, or shared memory. Then just open source the tiny program you wrote to use the GPL lib. I say if your going to make your work open source, then give people the right to go commercial with it if they want otherwise there is no incentive for them to give a crap about your code. You essentially force them to enslave their time to you if they decide to modify your code. When the FSF starts paying my rent and other bills I'll glady return the favor with GPL code. Because we're all in a hurry to spend tons of time writing code that isn't going to pay for itself.
CvIrrCamController - 3D head tracking lib to create window effect with webcam
IrrAR - Attach Irrlicht nodes to real life markers
http://www.nighsoft.com/