One particular question I have is whether POE fits/supports the publish/subscribe type of messaging? e.g., if more than one component wants to handle a POE event, how to do that?

As far as I know, there is no built-in mechanism for doing that in POE. It is trivially easy to implement yourself, though. Take a look at POE::Component::IRC's register code to see an example. Also, you might want to take a look at its _send_event subroutine to see how the events are actually sent to each registered session. Pretty straightforward stuff.

Update: in reply to:

Furthermore, if an event needs to be processed in several steps (sort of like Apache's request handling cycle), what's the best approach to do that in POE?

The easiest way is simply to post to the next event in the sequence. So event1 gets triggered, which does some stuff, then posts to event2. If you want some sort of centally managed way to do that, again, you'll have to do it yourself. But it wouldn't be too difficult.