Version:            (using KDE 4.1.0)
OS:                Linux
Installed from:    Ubuntu Packages

Running krunner to check processes' behavior, I saw that when you close a konqueror window its process is not killed, and stays wasting resources. The process is not idle waiting to be reused, as if you open another konqueror window it will create another process without touching the hidden/dormant ones. Those hidden/dormant processes react to SIGTERM, but I'm not sure they close the corresponding kio_http processes.
Depending on usage pattern and available RAM, memory can be quickly exausted by those processes, requiring manual intervention (killing processes, restarting session).
The ancient (and closed as fixed) bug 12309 reports a similar problem in the 1.9.x era konqueror, and as the new konq is a completely different beast I opened a new bug instead of repoening the old one.