Parse adds easy caching support for iOS and Android
blog.parse.com
blog.parse.com
BTW, Parse has the best "Quick Start" I have ever used for an API. Great stuff. A+ for removing any and all friction for a dev to take you on a test drive!
http://developer.apple.com/library/mac/#documentation/Cocoa/...
It has good examples of how to read and write to local files.
Another option is to use Three20's TTURLCache: http://api.three20.info/interface_t_t_u_r_l_cache.php
My biggest concern is how these are stored and whether I can trust queries to be cached for very long periods of time (like until the data updates).