[HerrMonnezza]

I'm not sure how they compare to Ruby's "ruote", but there are quite a few Python workflow managers and libraries out there.

GC3Pie (http://gc3pie.googlecode.com/) is a Python library for running many-task workflows featuring interruptible execution, interfaces to SGE, PBS and LSF clusters, and composition operators to build dynamic task dependencies (so, not just DAGs). Disclaimer: I'm one of the developers.

Weaver (http://bitbucket.org/pbui/weaver) is a Python front-end for building workflows that can run on top of the Makeflow engine, supporting SGE, Condor and WorkQueue as execution back-ends. (See the comment by its author "pbui" on another HN thread: http://news.ycombinator.com/item?id=4047100)

NiPyPe (http://nipy.sourceforge.net/nipype/) is a Python workflow engine especially targeted at Neuro-Imaging processing (but the core framework is generic, as far as I understand).

I'm pretty sure this list is not exhaustive: many people seem to be re-writing the same core functionality, coming from different fields and/or with slightly different requirements.