When looking at the Jobstream Runs - Timeline view, what determines which time zone is displayed?
AAI 6.5 and later
The time zone displayed on this page, being there could be schedulers from multiple time zones, is the User's Preferred time zone, which as of 6.5.1 can be set in the thick client.
You can set this in the thick client by going to File->Preferences and selecting the preferred time zone from the drop down box below: