This may depend on your data, but can you put a Visualization Panel in your Dashboard that simply displays a single value?
Then you could run a search for the most recent event and set the Visualization type to "Single Value"
So if your search was the following:
| eval Date = strftime(_time,"%m/%d/%Y %I:%M:%S %p") | eval text = "date is updated as of Today(".Date.")"| table text
All you would display in that specific panel was something like date is updated as of Today(06/29/2016 02:53:28 PM)
You can use a singlevalue panel to display. Like this
| gentimes start=-1 | eval t="Today (".strftime(starttime, "%m/%d/%Y %I:%M:%S %p").")"