I've also added support for timezones on the PlaceTime gregorian instant URIs so you can now write the date of the Apollo 11 moon landing in Eastern Daylight Time as:

http://placetime.com/instant/gregorian/1969-07-20T16:17:43-04:00

which is the same time as

http://placetime.com/instant/gregorian/1969-07-20T20:17:43Z

which in the UK would have been:

http://placetime.com/instant/gregorian/1969-07-20T21:17:43+01:00