Yes, there is shell scripting support in Maemo 5. You can use the default shell (ash) or you can download bash. bash is currently version 2.05.

There is also python 2.5 and perl 5.8.3, both of which you can call from the command line:
-> python -c 'print "hi"'
-> perl -e 'print "hi\n"'

If you want to interact with the device and its various features, one of the ways to do that is to use the dbus interface. There is lots of dbus documentation out there, here is an older maemo wiki entrey: http://maemo.org/community/wiki-closed/dbusguide/