Check for Salesforce.com Environment (isSandbox)

Check for Sandbox or Production in Apex

1. Create a Custom Setting called Environment Variables
2. Add Record in customer settings named: salesforce.com orgid with the orgid as the value__c
3. Then Assert the value with the current user.
4. isSandbox will return true for sandbox, false for production

 //Grab Environment Variables
    private static map<string,string> Settings{ 
        get{
            if(settings==null){
                map<string,Environment_Variable__c> s = Environment_Variable__c.getAll();
                settings = new map<string,string>();
                    for(string x: s.keySet()){
                    //iterate to make lowercase
                        settings.put(x.tolowercase(),s.get(x).Value__c);
                    }
            } 
            return settings;
         } 
         set;
    }
    //Check Custom Settings for match on orgid
    private static boolean isSandbox{
        get{
            if(isSandbox==null){
                isSandbox = true;
                if(Settings.containskey('salesforce orgid') && Settings.get('salesforce.com orgid')==userinfo.getOrganizationId()){
                    isSandbox = false;
                }    
            }
            system.debug('Environment = Sandbox?: '+ isSandbox);
            return isSandbox;
        }
        set;
    }