Any plans on allowing user-defined triggers to be deferrable?

I'd like to ensure that the creation of a department also implies the
creation of two to eight projects; no more, no less:

CREATE TABLE departments (
  department text primary key not null
);

CREATE TABLE projects (
project text primary key not null,
department text not null
  references departments(department)
  on delete cascade
  on update cascade
);

So it'd be nice to have an INSERT trigger that's fired on departments at
the end of the transaction to ensure that between two and eight projects
exist for the newly created department.

Is there no way to achieve the above stated goal in the server? Must I
rely on the application to enforce consistency?

Mike Mascari