I have been feeling a growing restlessness about people I respect a lot switching from java to python for more and more parts of their systems.
This affects my self assurance as consultant (am I making the wrong advice to my customers? am I missing a train?). With java I saw the light, it was a radical vision. C, C++, no more.
Seeing your entry and 2 level of links around it, I notice that I should bit the Unit Testing bullet first. I have not yet taken it seriously, just used the unit tests in place or adding here and there a new case. I mean, I do advice Unit Tests, I use them. But I have failed yet to see them as so rewarding. I bet it is because I'm working in more or less mature projects, and, in java, Unit Tests add to the build-bloat I'm facing.
I think I will not get it until I start a new project or extend significantly an existing one, with lots of new code.
I buy more the 20.000 lines argument of John. My lemma in the last year has been "I want the same functionality with 30% less code", and now I see why. I need mind share for starting new things. :-)
A pitfall may come: I fear a lot of the application programmers I'm seeing around in java would manage to spoil/fake Unit Tests and create interesting new breeds of runtime errors if they used python, perl or ruby. Unless Unit Tests are seriously peer reviewed.