to_json(now()) result doesn't have 'T' separator

# select to_json(now());
to_json
---------------------------------
"2013-12-20 15:53:39.098204-08"
(1 row)

I'd like to see it output "2013-12-20T15:53:39.098204-08" so it's
interchangeable with more systems.

http://en.wikipedia.org/wiki/ISO_8601#Combined_date_and_time_representationssays
'T' can be omitted "by mutual agreement".

I'm working with javascript/json systems that expect the 'T' to be there
however, so there's no mutual agreement happening.

Thoughts? I know I can hack around it by specifying my own date format, but
I'd really like to be able to use row_to_json and other functions without
specifying custom date formats everywhere.

Joe