There is about 3-4 threads in the forum talking about Barcode reader for N8XX. They pretty much all seems to be dead. But the answers are still vague. I am not a programmer or a coder so I have absolutely no idea on how to implement this.
Can we get a 2D/QR Bar-code reader for N900 and other tablets?
Some thing like this
And as I remember other N-Series phones came with the built-in app like this.

Other discussion on the older tablets.
http://talk.maemo.org/showthread.php?t=8836
http://talk.maemo.org/showthread.php?t=33032