Hmmn. I had done so already. Ran into the first bug where you don't get the plugins properly pulled down due to some plugin already being installed and fulfilling the requirements. Only had the copy-button. So I made sure to uninstall them all (and purged mBarcode). That let the plugins be pulled down automagically when reinstalling mBarcode again from the DEV-repo.

So yes, I already have the qrcode plugin, but I can not get it to add a contact from the code generated on the above linked site. The string read is displayed as: "MECARD:Testname;TEL;666666;;" and mBarcode give me the following options:
*Rating from Informed Individual
*Give opinion with Informed Individual
*Open iMode data (Does nothing)
*Search the Web

Taping Open iMode data does nothing. I get the click from the n900 confirming my tap, but nothing happens. The other options seem to work as intended (not familiar with Informed Individual so can't say for sure, but at least these options do something).

mbarcode-plugin-qrcode is listed as version 0.0.4-2.
mbarcode is listed as version 0.2.2-4
(I'll omit the rest of them)

So, anyone else able to add a contact from that site I linked using mbarcode? If so, we need to start comparing our devices =)