I've been looking for a way of multiplexing several ssh sessions. By that I mean the ability to type once, and the result happens in x ssh sessions. Thanks to someone on the FreeBSD UK user list I came across cssh (http://freshmeat.net/projects/cssh/). This does pretty much what I need, and so far I've had no problems with it.
What would be ideal though is functionality built into the window manager to do the same thing, so I 'tag' any number of windows, even varying applications, and my keyboard input, (maybe even mouse) is copied to all windows. For instance I could be typing into 3 ssh sessions and an instance of vi to record my typing.