Apparent referential integrity bug in PL/pgSQL

I have a function that operates on two tables A and B, such that B has a
foreign key on A, as follows:
INSERT INTO A (...) several times
INSERT INTO B (...) several times, with foreign keys pointing to the new
members of A
DELETE FROM A (...), possibly including some of the newly added members

Even though B's foreign key is defined ON DELETE CASCADE, I get a
referential integrity
violation when I run this function. If instead, I comment out the DELETE
statement, start a
transaction block, run the function, run the DELETE statement, and end
the transaction, no
errors occur. To run those statements with one function call, I need to
split the INSERTs and
DELETEs into separate functions, and call them separately from a third
function. I am using
version 7.2.2. Has this been corrected in the beta versions or can
someone confirm this for me?