I haven't used it because I use SSIS for my ETL needs, but have you checked out expressor Studio?
You could also check out ReactiveETL which is a rewrite of RhinoETL on CodePlex
If you are in an environment that is using SQL Server, you should have access to SSIS which is included with SQL Server and is able to attach to other databases using OLEDB or ODBC connections, so it doesn't have to be connecting to SQL Server in order to use it.
There have even been some presentations on using Powershell for ETL, one such presentation was put on by the App Dev Virtual Chapter of PASS.
For more details on that presentation check out the following link: