I have control of some important open source project, so I write an addendum to the license forbidding you, or your institution, from using it.
Now not only are you not allowed to download my stuff, but you can't update anything containing my stuff.
That's what Bruno Lowagie of Ghent is doing. He is engaged in a legal dispute with Belgian authorities over taxes on his AdSense ads. So he is writing a "Belgian Restriction" into his next license, forbidding the government from using the next version of his program, iText.
If this were just one program there might be little problem. But iText, which is used to manipulate PDF, RTF, and HTML files in Java, is also embedded in a host of other open source products, including Eclipse BIRT, Jasper Reports, Red Hat JBoss Seam, and Windward Reports.
In theory, the next time some Belgian bureaucrat tries to upgrade one of these other products they will be in violation of Lowagie's new license. Unless they want to settle the tax question.
So, on to the questions: