//One thing that frustrates me about how SQL Server handles NULL within unqiue constraints is that it does only allow one NULL value (as the article does a nice job of illustrating). It makes sense that it would allow >1 NULL value because they are in fact different values. Other RDBMS do allow this, so I kinda wish that SQL Server did also.//

NULLS are SQL's way of handling missing data and it is the worst one to do it. There are other ways to do it but current DBMS do not support it...Be it on ORACLE, DB2 or SQL Server, they are an aberration...