I can't seem to find a built-in mechanism in KDE for monitoring kernel and system error messages (critical ones are printed out to the console; they also appear in dmesg). I believe KDE used to have something like this (kdewall?) but there doesn't appear to be anything in KDE 3.2 beta 2.
I'm always running KDE, so I'd like to have a message pop up to let me know if there's a problem, eg. one of the drives in my RAID array is failing. Something that integrates with KDE's existing System Notifications would be ideal, so that you could choose whether you want to play a sound or display a message, etc. In addition, but somewhat less important, it would be nice if this could be extended to monitor log files for new messages, eg. Apache's error log.
I'm not currently a KDE developer, but I can code C++ on Linux so if there isn't already anything like this, maybe it would be worth me looking into it.