Splunk 6.3 and newer allows you to monitor the status of each search via Simple XML. You cannot monitor the dashboard as a whole, just individual searches.
Here is a link that acts as the technical reference for these events: http://docs.splunk.com/Documentation/Splunk/6.3.4/Viz/EventHandlerReference#Search_event_handlers
Here is an example of how to monitor these events and display text before showing the results when the search completes. You can replicate this pattern for other panels/charts/tables. Just remember to use unique tokens names (i.e., you can only use the identifier "search_msg" once).
<panel>
<title>Panel Title</title>
<html depends="$search_msg$">
<h3>$search_msg$</h3>
</html>
<chart rejects="$search_msg$">
<search>
<query>
<YOUR SEARCH>
</query>
<preview>
<set token="search_msg">Search is running</set>
</preview>
<error>
<set token="search_msg">Search encountered an error</set>
</error>
<cancel>
<set token="search_msg">Search was cancelled</set>
</cancel>
<fail>
<set token="search_msg">Search failed</set>
</fail>
<done>
<unset token="search_msg"/>
</done>
</search>
...
</chart>
</panel>
