>>15
つーことで省略値は常にUTC(GMT)のようです。
ｺﾝｽﾄﾗｸﾀで指定するしかないかなー

http://developer.apple.com/techpubs/webobjects/Reference/Javadoc/com/webobjects/foundation/NSTimestamp.html#timeZone()
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public NSTimeZone timeZone()

Deprecated. Deprecated in the Java Foundation framework. Do not use this method. All NSTimestamps are in UTC.

Returns:
This always returns NSTimeZone for GMT