Is there a way to have the Arduino software automatically switch to Serial Monitor after an upload?
I've searched the forums and the preferences.txt and don't see anything obvious.
There isn't, although it's a frequently requested feature so I'll take a look at it for Arduino 0012. I imagine that if you had the serial monitor open when you pressed the upload button, it would automatically reopen when the upload completed (probably only if it was successful, though).
Is there a way to have the Arduino software automatically switch to Serial Monitor after an upload?
As mentioned above, no.
One work around (at least on Mac OS X) is to click on the serial monitor button in the GUI while the code is compiling/uploading. While the click doesn't register immediately once the upload has finished it will register and the serial monitor will open. Not quite automatic but for me better than waiting around for the upload to finish and then missing the initial serial output.
Of course, if the compile/upload fails you still swap to the serial monitor and have to recompile to see whatever the error was, so it's not perfect. 
--Phil.
There isn't, although it's a frequently requested feature so I'll take a look at it for Arduino 0012.
Even a keyboard shortcut for the button would be a good start.
I imagine that if you had the serial monitor open when you pressed the upload button, it would automatically reopen when the upload completed
Hmmm, interesting, I hadn't thought of it operating like that. I was envisaging a preference (bingo!) or default state that always switched to the console. But your suggestion might work better, although it would still require you to open the serial console for the first time each session.
(probably only if it was successful, though).
Yeah, you don't want to miss the diagnostic messages if it fails and wonder why the output from your new code is the same as the old. 
--Phil.