How can I track stale content and alert content owners to it? I'm building a new version of a corporate web site, and want to make it easy for content owners to keep their content updated regularly.  

In the current site, most of the content has not been updated for years, and it's unclear who is responsible for various pieces of content.  In the new site, each part of the site (usually a section but in some cases individual pages) will have a person or group of people designated as the owners of that content, and responsible for keeping it updated.  I'm pretty certain, however, that they won't do anything unless they are prodded.

One possibility is to add a Dated boolean to all nodes to flag certain content as something that will go out-of-date regularly, such as an About Us page that says "we currently have 127 locations across states X, Y, and Z in the U.S. and provinces A, B, and C in Canada.  Then there would need to be some mechanism to send e-mail notifications to the designated owner of that content after (for instance) 3 months, including the content and a link to edit it, and asking them if it is still accurate.   Content not marked "Dated" could have e-mails sent out after (say) 9 months, or whatever time frame seems logical.

I've searched for a module that helps solve this problem, but have found nothing.  How would you go about doing this, or something like it (if you have an alternate idea to solve the problem)?
It's been awhile since you asked and I'm assuming you found an answer. For those who come across this post, the Rules module should handle this requirement. 


Create a rule to react when content is viewed, which should suffice as a trigger. 
Add a condition to run a data comparison on node modification date or write custom PHP comparison code.
Set the rule to send an email to the node's author.