Hmm, I guess the problem is to start an xterm and actually delivering the message there. I would probably start the X term with another script that would connect the my log-analyzing process via a unix socket or some other form of IPC and receive the message from there.

But I didn't really understand your problem: Do you want a new xterm for every log-message or only one xterm per logfile?

If you want one xterm per logfile the best would probably just to startup the xterms and run a tail there.