I'm not sure what is so special about it? SQL Server allows expressions in ORDER BY clause.

>I just stumbled across this little gem
>
>

>declare @x table ( i1 int, i2 int )
>insert into @x values ( 1, 2 )
>insert into @x values ( 2, 1 )
>
>select *
>   from @x
>   order by
>       case when 1 = 1
>          then i1
>          else i2
>       end
>
>select *
>   from @x
>   order by
>       case when 1 != 1
>          then i1
>          else i2
>       end
>

>
>Works in 2000 and 2005. The example is a bogus when clause, more practically it'll be a parameter to your stored proc to pick the column to use for the output order. Go purge all that dynamic SQL you have just to get alternate output order.