I've used various forks (mostly the ngmoco fork) of Nick Kallen's excellent cache_money for several Rails 2.3 based project, but we're now making the leap to Rails 3 which, thanks to the introduction of ActiveRelation, does not work with the popular forks of cache_money.
Is there a fork of cache_money, or an equivalent write-through cache, that is compatible with Rails 3 ?
Last week I launched a new write-through-cache gem for Rails 3, see https://github.com/orslumen/record-cache.
The reason I built it, is because we were using cache money and recently migrated to Rails 3. So chances are it may also serve you well.