"When was the data on this dashboard last updated?" This is perhaps the most common question of data workers. If you use Tableau Online, you may start hearing this question A LOT from your users because the <Data Update Time> does not actually get updated when your on-premise data is refreshed through Tableau's recommend use of command line tools found here:
This means that if your data sources are on premise (say SQL Server, or Excel), there's no simple way to display to the user: "Last Updated: 11/4/2013 4:00pm" on the title of your dashboard unless you manually republish your data source every 15 minutes. I just went through this unfortunate discovery through Tableau Support until this issue was labeled a "feature request".
Tableau is far too good to not fix an oversight like this. Please vote this up so it can get fixed ASAP!