I was working with a customer who had a tag used for associating a specific document with a geography/region as shown in the image below. Managed metadata columns are a feature in SharePoint 2010 permitting you to add specialized/pre-defined term sets to a particular content type. In my customer’s case, they had a document library with a Geography column.
Elevated users could add documents, specifying a value for the Geography field without issue. ‘Normal’ (Non-site admin) users could also specify a value and save a document to the library without error; however, the field would not be populated with a value upon saving the document. (The managed metadata column would simply be blank.)