heroku と postgresql を使用している私のアプリケーションは 100% ダウンしており、アプリケーションはH10 error. 以下のログが問題のルートだと思います。
2012-08-28T19:17:44+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.3/lib/active_record/connection_adapters/postgresql_adapter.rb:1194:in `initialize': FATAL: role "arseiiyfkbqalv" is not permitted to log in (PGError)
(I just your case as I work at the heroku data team)
You deprovisioned your dev database, but have not updated your dyno's configuration to make it connect to a new one. You can do that by running heroku pg:promote HEROKU_POSTGRESQL_<NEW COLOR> --app your-app
You can view a list of databases currently on your app by running heroku pg:info --app your-app. The database that is promoted as the primary will also show that it is DATABASE_URL.