To elaborate, I have found the rsync used in my (most?) streaming replication setups is 10x or more faster than pg_dump. If your job specs required a pg_dump output file it would be fairly simple to do the following (moree or less):
1. setup a replicant (even on the same machine but different drive if you wanted)
2. make sure the replicant is off
3. rsync the data dir to the replicant
4. turn on the replicant
5. execute pg_dump on the replicant
regards,
/r/b