[robbak]

Probably via inetd, but the diference is minimal.

inetd (the internet daemon) is a single daemon that listens on multiple ports, and spawns processes to deal with connections that occur.
As inetd can end up running programs that you are unaware of, it is a source of security holes if you are not aware of what it is doing. inetd also handles on it's own several simple (and now largely unused) services, which could be security problems if there are unknown holes in it's decades-old code. That said, it can also be configured to run things like tcpwrappers which are good things that increase system security.

There is very little difference, security wise, to running a daemon standalone, and adding that daemon to an already running inetd. There are, however, performance and speed issues: inetd only spawns the process when it is needed, so the process does not consume resources when no one is using it. However, there is an overhead on each connection as inetd spawns a new process to handle it.
Generally, a heavily used service will be run standalone. An infrequently used service might be left on inetd's hands.