Debug and Release build in Visual Studio Express edition
So.. where did it go? It took me a couple of minutes to find it but it seems to be an "advanced" feature :-)
Go to:
Tools --> Options...
Check the
'Show all settings' box in the lower right corner
Then go to:
Projects and Solutions --> General
Check the
'Show advanced build configurations' box somewhere in the middle section.

(Click to enlarge)
Now you will have the option to quickly toggle between debug and release builds in the toolbar and see all sort of
'advanced' features in the
solution and
project properties.
PS:
This also gives access to the option to use tabs instead of spaces. Don't know why the default is spaces. I want to decide myself how many spaces a tab should be ;-).