The behavior I m observing with the Mongoid adapter is that it ll save time fields with the current system timezone into the database. Note that it s the system time and not Rail s environment s Time.zone. If I change the system timezone, then subsequent saves will pick up the current system timezone.
# system currently at UTC -7
@record.time_attribute = Time.now.utc
@record.save
# in mongo, the value is "time_attribute" : "Mon May 17 2010 12:00:00 GMT-0700 (QYZST)"
@record.reload.time_attribute.utc? # false