After further inspection, it seems that the RSS feed pubtime for posts is output in *local time* as determined by the time offset in the options page used by WP1.5 instead of the UTC. Shouldn’t the UTC always be used for the RSS feed?
Here is what I do: two posts, one with an offset of -5, one with no offset. then i look at the RSS feed. the two pub times are different by 5 hours. It seems to me they should stay the same since there is no hint of a time zone in the RSS feed. Am I the only one having this problem?