Not really. Erlang is for reliable concurrent transactional computing while X10 is for parallel scientific computing. You might say that X10 aims to replace Fortan.
Then it's doomed IMO, since there's Fortress (http://projectfortress.sun.com/) out threre developed at the Sun Labs and which seems to be a better candidate to replace Fortran.
DARPA funded X10 and Fortress at the same time to provide options for a future "high-productivity" HPC programming language; it's not clear that either one has gotten any traction yet.
Well really, C++ is rapidly replacing Fortran for scientific computing, but it ain't all that much better for it. I'm excited about the idea that this replaces MPI.
Physicists at my school/uni (in France) use Python with appropriate libs, but I don't know if it's the general case here, since I know physicists from near university use C++ (badly from what I saw, but that's an other story).
I'm a physicist, and I use Python (with scipy/numpy when appropriate) when I can get away with it (ie for small to medium-sized calculations).
For big calculations, though, where what you can do is limited by performance, there's no getting away from C++ or Fortran. Python has a huge performance overhead (I have learned this the hard way).
