I've worked on Death March projects in the Java world - projects that are destined to fail from the beginning because of some combination of poor management and unwieldy, complex technology, usually spanning multiple systems and often tied to a waterfall approach.
Rails and Django are touted as Agile development technologies, which means they are oriented towards being able to respond to change quickly.
Does this mean they are immune to the Death March scenarios of large enterprise systems? Or is there still room for enough complexity in a Rails/Django project that it could spiral out of control just as a Java project would?
Of course it is. I have personal experience of working on several Django projects which have become death marches.
You can have all the agile development technology in the world, but if your company does not fully embrace agile concepts then it won't help you avoid the death march. If the management demands a product to be delivered on a certain date, and that it includes a certain set of features, then using a framework won't help: you're still stuck working as fast as you can until they're satisfied. If that means a death march, then a death march it is.