I found a somewhat verbose code in a sample. I do not know what worries me the most: that someone thought it was easier to write this many lines of inefficient code or the fact that may be it was not simple enough to find the method in the documentation.
The purpose of the iterator is to provide a mean to sequentially access items of a collection, without exposing the internal structure of the collection.
The TPL DataFlow exposes classes to manipulate data asynchronously. It is based on the Task library and on two the interfaces ISourceBlock<T> and ITargetBlock<T>.
Several RFC are related to the WebDAV protocol. I have been wondering if this should not be an interresting starting point to both a CMS and an activity management server. In a way, an activity management like FlowGroup could simply expose vCard and vCalendar items, the customization consisting in defining business rules on how to aggregation Organizational Units informations to create the vCard, or when to create a vEvent, a vJournal or a vTodo. These would be wrappers around related documents that would keep track of the business data.