When a job is running in Hudson, the build directory is available as builds/number symlink. This is useful for running tail -f on the logfile, but since the build number changes, you have to check for the current build number each time. If Hudson can create a symlink called builds/last (or builds/running) while the job is running, it would be easier to use the same shell command from history each time, e.g.

tail -f builds/last/log

regardless of the build number.