It seems that the on screen esc-key works as a meta key, at least for some apps in xterm on the N900.

To be frank what I noticed was that pressing esc and then arrow or number swiches irssi-window (this is traditionally done w/ the meta key as far as I know..

(sorry if I'm poking an old thread but this was a pain for me to find so I figured I'd help out fellow IRCers )