Design it one step at a time. First learn to set up a daemon and talk to it through a socket port. Then setup the daemon to start x number of threads when it initiates, and just put the threads to sleep. Then figure out the thread code blocks needed for watching your cards. One step at a time. It may be easier to log to different files for each thread to avoid clashes when writing to the log files. It sounds pretty complex, and I doubt if someone is going to be able to provide an "instant skeleton" for it. But you might get lucky. :-)

So maybe you should repost your question, like: "How do I setup a daemon and talk to it through sockets?" That is your first big step. (As always, groups.google for it first..."perl daemon socket communication" gets you some code on the first page.)