@nongli: These timezones are from the Olson database (which Joda uses).  I'm fine with ordering the list alphabetically (or some other way).  It seems like we just need to come with what our definitions will be and then stick to them.

@rdblue, I agree that we should always store in utc (unless we are without a reference frame).  The timezone id could be recorded at the column level if it is shared (in that case we could also use the standard names and enumerations wouldn't matter).  However, for the encoding for record by record, I think we need to come up with a canonical enumeration to minimize storage costs (and not change the enumeration except as part of the format version bump).