Application Template - Feature is not installed in this farm

You may see this type of error if you are creating a site using one of Microsoft's application templates as the template for your new site.

For example, trying to install the HelpDesk site, you would see this error: Feature '75a0fea7-12fe-4cad-a1b2-525fa776c07e' is not installed in this farm

Oops!  First, check in Central Admin > Operations > Solution Management.  You should see the template that you are trying to create was successfully installed.  If it is... you most likely forgot to deploy the ApplicationTemplateCore.wsp solution first.    Download it and install it as you did your template that isn't working.