Perhaps use http://code.google.com/p/kitty-cache/? Port it to scala?
Here's a quick brain dump of what I had in mind. Happy to discuss.
#6 - changed ProcessingContext.cache to ProcessingContext.item so the
word "cache" does not confuse.
#6 added concurrent linked hash map library
#6 - Local in memory cache
#6 - in memory caching of small files
#6 - wip static content handler test cases
#6 - unit tests of static content handler