Since it seems this feature didn't made it's way to the community edition, but in the page settings actually everything is ready for it, I guess it would just be matter of plugging a provider.

Any infos, hint even from dnn staff on how to carry on this little project would be welcome. I'll start my research trying to build a simple in-memory provider, then eventually move to the file based provider.

Hallo Cathal! Thank you for you kind reply. If there are 3rd party implementaions this would avoid me to build mine already... could you please point me to any one of those 3rd party providers since I wasn't able to find a single one please?
I think due to the nature of DNN which is all db-based this is a must-have feature, even for the poor guys that cannot afford the commercial edition, so buying a third party provider is an option!
If you can point me to some of those I will be immensely grateful

Hallo Cathal. Of course it's for unauthenticated user but that's 90% of visits for non social-only sites, like for example news sites, or even e-commerce until you log to buy.
Cutting the whole page lifecycle it's a big benefit even with short cache duration like 30 sec or 1-2 minutes.
Module caching of course is great as well even if to a minor extent. I guess being able to leverage both is the perfect solution, in particular with "high" traffic sites that you could run without having a supercomputer to host your sql server istance (did you take a look at NuoDB?).
I'll take a better look at the link you provided (which was the only one I found as well) but I think that's more at module level and written explicitly for distributed caching (so no simple in-memory, file or db storage).
The only resource I found about the abstract class to inherit to write a custom provider for DNN output page caching is:
https://github.com/neogic/DotNetNuke_...
Do you think this is still the actual class to be used to build a custom provider? Could it be a good start?