I'd love to know more about the technical details of how DNN caches data. I'd also be interested to know if anyone can answer the following question with regard to asp.net 2.0 in general:

I'd like to cache a page using the 'Page Output Cache' however ideally I'd like to cache it on the server for longer than I would like to cache it on the client e.g. I'd like to cache it on the server for an hour say and on the client for 15 minutes.

Is this possible? And if so how?

I'm actually trying to understand how to write advanced caching techniques for my own website - I have no intention of playing with DNN's.

Do you have any insights into how to go about writing a 'good' caching system such as what DNN uses?

There are myraids of articles on caching if you do some web searches... While I never needed to deal with that end of things in "Games Development" you might try some searches based on Games Dev graphics, object etc. caching. While these days alot of this stuff is kept rather "highly secretive" by development houses you might find some info out there which would be Java based or pseudo but logic is the logic. Caching items in games is standard practice in many areas of the applications and pretty much are "state of the art" resulting in seemless transitions and application flow. Gamedev.net would be a good place to look. Caching schemes vary so for best performance you want generally find something that fit's your data structures you will be using.

http://www.tangosol.com/coherence-overview.jsp

http://www.alachisoft.com/articles/domain_objects_caching_pattern.htm

http://www.Gamedev.net

Also check the various code archives like codeproject.com etc.