We were meeting with AdHost today and I gave a quick 30-minute spiel on what we improved in IIS7 when it comes to Shared Hosting. Here is the list (not necessarily complete):
1) Shared Configuration
You can have the central IIS configuration file (applicationhost.config - the metabase is gone) on a central server and share it across multiple front ends. Not limited to Shared Hosting, but most Hosters love it. More info: http://learn.iis.net/page.aspx/264/shared-configuration/
2) Delegated Configuration
IIS configuration can be stored either centrally like in IIS 6.0 or a hoster can allow a customer to configure his own settings. No need to call up the hoster if default documents or authentication settings need to be changed. These settings can be delegated on a feature by feature basis or even on a per configuration property level. Delegated configuration settings are shared with ASP.NET in web.config files. More information: http://learn.iis.net/page.aspx/157/how-to-use-configuration-delegation-in-iis-7/
3) New Publishing Stack
IIS7 offers a brand-new publishing stack, i.e. FTP7 supporting SSL, WebDAV (map a drive in Explorer to connect to your web-site) and a new version of Frontpage Server Extensions.
More information:
FTP7: http://learn.iis.net/page.aspx/356/ftp-7-for-iis-70/
WebDAV: http://learn.iis.net/page.aspx/357/webdav-for-iis-70/
Frontpage Server Extensions: http://learn.iis.net/page.aspx/358/frontpage-server-extensions-fpse-for-iis-70/
4) Improved PHP Support
Wordpress, Drupal, phpBB are very popular and there are tons of other pre-packaged PHP applications out there. But PHP didn't run to well on the Windows platform. This changed with the FastCGI feature that was introduced for IIS 6.0 and 7.0. FastCGI is shipped as part of IIS in Windows Server 2008.
FastCGI/PHP: http://learn.iis.net/page.aspx/208/fastcgi-with-php/
MySQL: http://learn.iis.net/page.aspx/353/mysql-server/
And something else. The SQL Server drivers for PHP were slowing things down quite a bit. But not anymore. There is new PHP driver available written by the SQL Server team itself: http://www.m