Mathematica is a great language, but: 1. it is too slow 2. It is often hard to read 3. It gives sence to every keystroke. You press escape by occasion and it goes in a code as a new symbol, w/o error. Nasty. 3. I know 5-th version. It does not allow to track the source as SLIME does. This feature as absolutely necessary for serious development
So, in fact, Mathematica do not scale well IMO. -- http://mail.python.org/mailman/listinfo/python-list