I am running KDE 4.4.5 on Gentoo Linux ~amd64. On Windows XP, if you are using a web browser and an instant messenger simultaneously, have the web browser as your active window and receive an instant message, the button for your instant messenger's window on the task bar will begin to blink to tell you that there is something new that you might want to see.

Often in KDE, I am using a web browser and irssi in a terminal window. I know if I have multiple tabs open in the terminal and something new happens in the irssi tab, I see the tab's name turn purple. However, if I am in my web browser and something new happens in one of the terminal windows, I see nothing on the task manager to notify me of that. Is there any way that I can configure KDE to give me such notifications?

since you're using a teminal based irc client I don't see how (not that I would know), it seems to me you need to run something with a system tray icon or osd messaging capability like Konversation.

You can get Irssi to perform a "system bell" event, which can cause Konsole to request attention.

Does "monitor for activity" under konsole's view menu do it? You would want to enable that and, under settings->notification, set "Activity in Monitored Session" to "Mark Taskbar Entry" and/or "Show a message in a popup", depending on your personal taste.

"Bell in Non-Visible Session" is required in this case.