Ran into something really unexpected, but then I've never tried using 
inherited tables.
I have a master table (named master) that has two child tables.
create table master (
   id serial,
   foo varchar(20),
   bar varchar(20),
   constraint foobar_master unique (foo,bar)
);
Now when I do this with just a table, the unique constraint works.
But when I have child tables:
create table slave (
   status varchar(20),
   deleted boolean default false
) inherits (master);
I seem to lose that unique constraint.  Which makes for a HUGE problem.
Am I missing something in the fine print?