If the process has no connection with standard input, you can try the disown built-in. Using option -h it marks the job leaving it immune from hang-up signals (like those ones sent upon logout). In practice disown detaches the job from the parent shell and it will continue to run independently from what happens to the shell that can be terminated.
Please, note that disown may not work on stopped (paused) jobs: maybe it's safer to keep it running.
You can give it a try, but I second the suggestion given by fordeck: the screen utility is very suitable for this kind of operations. Take in mind that you can resume a screen session even from another (remote) machine and you can still watch the standard output (not possible with disown, since in this case the connection between the standard output and the terminal is definitively lost).
Last edited by colucix; 11-16-2010 at 12:56 PM.
Reason: added note on stopped jobs