While running WireShark I did a follow up post to one of my sites using ScribeFire. Something I learned was that it seems like ScribeFire is doing the right thing.
A portion of the capture:
<value>
<dateTime.iso8601>20080828T16:10:48Z</dateTime.iso8601>
</value>
This means that Drupal may not be handling this correctly. For a while I allowed users to choose their own timezone. I changed my profile to be a little different than the site setting. I thought maybe that would be causing the problem, but I changed the db to revert it back. This had no change.
More investigation needed before I can file a bug report.