Stackage is an infrastructure to create stable builds of complete package sets (henceforth we call them “snapshots”). Think “stable Hackage”.
There is an upcoming Stackage server (a la Hackage server) which will be released for beta in the next month. This can be used as a drop-in replacement for Hackage, by adding a link (as from here to the repo in your .cabal file:
cabal update and then now everything that you install should build and pass tests.