unrecognized language plpgsql

 Hello.

 This is the error message I get when trying to create a function in
 plpgsql:

     ERROR: Unrecognized language specified in a CREATE FUNCTION: 'plpgsql'.
    Recognixed languages are sql, C, internal, and created procedural
    languages.

 I use Debian packages for Pg 7.1 BETA4. I thought plpgsql was integrated by
 default, but see it is not so.

 Might I install plpgsql as procedural language or am I doing something
 wrong?.

 Thanks.

                                     David