Spark is a view engine for Asp.Net Mvc and Castle Project MonoRail frameworks. The idea is to allow the html to dominate the flow and the code to fit seamlessly.
I asked him afterward if he would be interested in helping update the releases on Codeplex and he kindly agreed, in fact the new bits on codeplex and release notes were put together by Erik, so be sure to thank him for that. Hopefully this is just the first step in getting that larger support base I've been angling for.
Expiring the cached output when it reaches a certain age, or when unused for a certain period, always involves a trade-off... To have ultimate control over your cached data you may provide an ICacheSignal that will fire an event when the data changes.