The function pg_sequence_last_value() was added to underlie the pg_sequences view, and it's the only way I'm aware of from userspace to directly get the last value of a sequence globally (i.e., not within the current session like currval()/lastval()). Obviously you can join to the pg_sequences view, but that's sometimes unnecessarily cumbersome since it doesn't expose the relid of the sequence.
When that function got added it apparently wasn't added to the docs, though I'm not sure if that was intentional or not. Does anyone have any objections to documenting pg_sequence_last_value() in the sequence manipulation functions doc page? James