Long Running Tasks - What Pattern?

Have you looked into the daemons gem? It might possibly fit your need.

RSL

http://backgroundrb.rubyforge.org/

It depends on what kind of task you are planning on offloading. If it
is something the user needs to wait for, perhaps you could provide a
progress bar? Otherwise a system message or email when completed
should work. Again it depends on what this process is doing and
whether it "makes sense".

-Shawn