Commercial Apps Can Link With GPL'd Libraries?

tommyd writes: "In the discussion following this editorial at Freshmeat, Matthias Ettrich of KDE fame claims that it's OK for a commercial application to use GPL'd libraries. I've never heard such a claim before. It would certainly make this plea from RMS redundant (not to mention the LGPL), but could spell bad things for GPL'd software generally. What's the Slashdot community's opinion?"