After finding out that the caching API is severely divergent depending if you're targeting Windows Azure or Windows Server, I'm concerned that Microsoft isn't going to continue to develop AppFabric for Windows Server. Does anyone know if AppFabric for Windows Server is still being supported/developed?
It is currently being supported by Windows Server 2012: http://blogs.msdn.com/b/workflowteam/archive/2012/10/25/appfabric-now-supported-on-windows-server-2012.aspx
Microsoft has released 4 cumulative updates for AppFabric (latest one being April 2013): http://support.microsoft.com/kb/2800726
I think your answer is that it is being supported. However, I have not seen any publishings/blog posts about the technology unfortunately. All the development on distributed caching has been done on the Azure side, where they have 3 different caching API offerings (albeit one being deprecated and another in preview mode).
I personally have stopped using it, since the API causes problems with the Azure SDK/API and there are better options out there if you have a hybrid environment with Linux (i.e. Redis)
Edit (10/06/2014): Note Microsoft's guidance on using the AppFabric Cache for Azure..."We just announced support for the Azure Redis Cache, and we recommend new development use this cache." AND "If you recommend Redis, why do you have Managed Cache, an option that you do not recommend? To support customers who made investments into Velocity Cache, who have dependency on it in their apps, to give them as much time as they need to move to the Redis cache."
Link: https://azure.microsoft.com/en-us/pricing/details/cache/
Looks like Microsoft (at least for Azure) is recommending, developers start using the Redis Cache. May not apply for Windows Server Caching, but I with the slower release cadence of AppFabric...I would strongly look at other options.