Sometimes you just need to know if a user is a farm admin; conveniently SharePoint provides a couple of static methods on the SPFarm object to check this:

if( SPFarm.CurrentUserIsAdministrator() ) { ... }

Neat, but one tip – it’s not obvious but it seems that if you want to check this within a content web application, you have to use the method that accepts a boolean and that bool needs to be true:

if( SPFarm.CurrentUserIsAdministrator(true) ) { ... }

Otherwise you will only ever get a ‘false’ response.