Savepoint/Rollback in functions

I am running postgres 8.1.2 on both a windows and Linux platform.

The primary method of managing business logic is through the use of 
functions.  Our primary access to the database is by using PSQL (pg/psql).

The problem that I am having is that we need to execute and implement 
"SAVEPOINT" and "ROLLBACK" functionality inside of FUNCTIONS.  The 
"SAAVEPOINT/ROLLBACK" works fine interactively.  At the present time the 
documentation does not seem to be definitive on the functionality of 
this, BUT, we placed "SAVEPOINT/ROLLBACK" commands in a test function 
and the function failed.

Question 1:  does pg/psql functions allow "SAVEPOINT/ROLLBACK" 
functionality? (if so how?)

Question 2:  if the answer to question 1 is "NO", what would be required 
to get this implemented in the standard product?

Thanks in advance for any information and help.

Scott.