SharePoint Designer Control in SharePoint 2010
The SharePoint Designer control in SharePoint 2010 in Central Administration is such a long anticipated feature and a heaven-sent.

Administrators can control Designer access and other configuration settings at a web application level:

Enable SharePoint Designer – Lets you configure whether any site collection and/or subweb under a specific web application can be opened in SharePoint Designer. BINGO!
Enable Detaching Pages…… – If users open the site collection and/or subweb in Designer whether users have the ability to modify the original forms or pages, i.e. detach that from the out of the box site definition.
Enable Customizing Master Pages and Layout Pages…. Pretty select explanatory whether you want to allow users to change master page and page layout objects in a site collection and/or subwebs….
Enable Managing of the Web Site URL Structure… Enables or disables the site URL structure and its contents. When checked, SharePoint Designer displays the All Files options in the Navigation pane allowing users to view and edit any file on the site. When unchecked, the All Files option doesn’t appear in the Navigation pane.
So this control over Designer is very useful in a large enterprise scale deployment where some power users can become a nightmare for SharePoint Administrators.
Comment if you think this is a useful feature and think that this hook would have been additionally useful at a lower level such as the Site Collection.