database DLLs and implicit commit

I've been taught that in RDBMS any DDL always causes an implicit commit, ending any active transaction at the time the DDL is issued.

Now I found this page on the PostgreSQL wiki that states that PostgreSQL is able to perform DDL statements in a transaction, making them atomic and rollback-able.

But does that change anything with respect to the implicit commit about the DDL? Is it still executed when the DDL is issued?