So I have been asked the following question: When a site collection or one of it's web sites are deleted, is this data purged from the database, or is this data otherwise marked as deleted but kept as entries?
Any ideas? Thanks.
Any data that is not going to the recyle bin is directly deleted. You need special workflows (check codeplex.com) to capture it.
Documents, ListItems and Lists are going to the recycle bin. Anything else need a database backup.
Webs are irrecoverable from what I know (aside from restoring from a backup or snapshot), Site Collections might be the same.