Is there anything like this for Python? I know there's Google App Engine, but to deploy a Django app it seems like you need to specifically write your app to work there. Where as this appears to be a solution to deploy any rails based app as is.
Well, almost. You may have to modify existing apps to deal with having a read-only filesystem, e.g. anything that accepts user uploads.
and it has to run on postgres
heroku is sweet. You can do a lot for free there if you don't need much database space and all your requests are quick (or you can use http caching effectively).