BackgroundDRb makes it easier to leverage DRb and takes care of a lot
of details for you (assuming you're not on win32). You can use DRb
directly, but you'll have to figure out ways to connect it up to your
Rails controllers, daemonize a ruby process and keep tabs on currently
running tasks. All of that isn't hard, it just takes time away from
what you really want to accomplish.
It's still in alpha, but so far it has been solid for me. YMMV