I don't think so. This is certainly something that requires scripting.
Since FitArtboard to Artwork bound and Fit artboard to Selected, are available under object->Artboard menu , you can definately Create a customized shortcut for this functionality and use them
to create a customized keyboard shortcut do this:
Edit->keyboard shortcuts->choose menu commands->object->Artboard-> double click on the " Fit to Artwork Bounds" in the line of shortcut column and provide a custom shortcut.
As Sanjay said. It is indeed a very useful command and was the first edit I made to the keyboard shortcuts.
It seems that is a new function in CS5 - I couldn't find this option in the menu commands of the short cut dialog in CS4.
You're right, It's not in CS4.
It's not in CS5, either.
Fit to Artwork Bounds IS in CS5 and can be included in an action too.