Reactive ETL is a rewrite of Rhino ETL using the reactive extensions for .Net.
Rhino ETL is a great and easy to use ETL in C# that rely on "IEnumerable" and "yield return" to provide ETL pipelines.
While Rhino ETL is great, the "Enumerable" pattern is a pulling technic, not really adapted to queues and pipelines. By using this pattern, you end up writing too much code for simple operations.
For an ETL the Observable pattern is more appropriate because it's a push technique. You define your queues and pipelines by chaining methods, in the same way you write Linq expressions, and then you tell your datasources to push data to the pipelines.