If farm admin does not have local admin rights
In case the farm admin account does not have local administrator rights on the SharePoint machine where the Preview Gatherer service is installed (Central Administration machine), it will not be possible to view the Gatherer status page. Instead, you would see an error message that the communication with the service could not be established. There is a workaround for this issue.
To assign rights for the Gatherer service to create its WCF end point (assuming it runs as a non-admin account), run the following command (applies to Windows 2008):
netsh http add urlacl url=http://+:4166/Gatherer/Control user=DOMAIN\user
where DOMAIN\user has to be changed so that it is equal to the account the Gatherer is using.