stored procedures

One of our DBAs is asking about pg's support for stored procedures. He
says he can't find any docs about it. As I understand it, what he wants
is to be able store a series of sql statements that would be executed
when called. He doesn't want to have to go to an external language like
perl or tcl to do this, and says this sort of thing is standard
procedure on Oracle, SQLServer, etc. He sent me the definition shown
below, about what SPs are. Does PG support this? Can someone give me a
link to some docs that I can send to him? Thanks.

Petre Scheie

--snip--

Stored procedures assist in achieving a consistent implementation of
logic across applications. SPs have SQL statements and program logic.
Each application needing to perform that task can then simply execute
the stored procedure. Coding business logic into a single stored
procedure also offers a single point of control for ensuring that
business rules are correctly enforced.Stored procedures can also improve
performance. Many tasks are implemented as a series of SQL statements.
Conditional logic applied to the results of the first SQL statements
determines which subsequent SQL statements are executed. SQL statements
and conditional logic are written into a stored procedure, they become
part of a single execution plan on the server.