In Appfog how to install the latest version of Nodejs/ and on the services provided, can Mongodb be upgraded to 2.4.x
AppFog does not support SPECIFIC versions of node, just version "families".
For example, to use 0.8.x, use the CLI:
af push --runtime=node08
This would give you 0.8.14 (at the time of this writing)
MongoDB 2.x support is planned in their road map...
See: