Here's a great MOSS feature for large organizations with concerns about users that should not be deleting sites; where the Site Collection Administrator may have given a particular user elevated permissions that they should not have been given. I have some client's asking about some further description around this since they are new to SharePoint and have not had the prior experiences with sites recovery and working with content.

http://www.codeplex.com/governance

http://www.codeplex.com/governance/Release/ProjectReleases.aspx?ReleaseId=3830

There is no OOTB setting to prevent this without proper training of Misys Site Collection Administrators. They should know what level of permissions to assign their departmental users. This is a feature to archive and email the Site Collection Admin that the site has been deleted. When you build sites for your users, be sure to assign someone in the IT staff as one of the two Admins on the site so you will receive the email as well.

A Site Collection Admin can give someone full permissions to a site collection or subweb allowing them to accidentally delete any site. This feature is like a second stage recycle bin and prevents you from having to get the SQL folks like Doug involved.

If a user was to delete a subweb you could restore a stsadm.exe scripted backup of the site collection, but this feature takes the last state of the content prior to deletion and saves it to a local UNC path (preferably, one of the front end webs with a Share that has sufficient space.

Keep in mind that if you deploy this feature, then a site collection, no matter how large will be archived accordingly. This is why it is good to set EACH site collection with an appropriate Quota Template, say, no larger than 10GB.

Of course, as always with Codeplex 'source', I would recommend deploying / testing on a Dev instance or VHD.