SHA1 on postgres 8.3

I am trying to port a MySQL db to postgres 8.3rc1.
In MySQL I have a function SHA1, which is critical for storing and
authenticating passwords.
I see some old posts on how to add this function myself.  see:
http://raveica.comdurav.com/blog/programming/how-do-i-add-sha1-to-postgresql/

Has sha1 been added to the standard postgres 8.3?  or do I still need
to build my own version?
Are there updated instructions for this for 8.3?

thanks, Jon