OK, this is perhaps only something of interest to theoretical high energy physicists, superstring theorists and the like: I've successfully installed and tested the computer algebra system Cadabra in Easy Debian. Cadabra is now available in Debian squeeze and can be installed from there with
(texlive-latex3 is a missing dependency). On my installation, it was just barely possible given the space limitations, but once installed it runs nicely and fast with "debbie xcadabra".