Was reading the docs and stumbled across what I believe is a mistake.
There is a mistake in Table 9-25
the result of to_char(148.5,'999D999') should be ' 148.500',
the docs list it as ' 148,500'
http://www.postgresql.org/docs/8.4/interactive/functions-formatting.html
and
http://developer.postgresql.org/pgdocs/postgres/functions-formatting.html