According to Dominique Peretti:
More seriously, on the french layout, shift-alt-l is the way to type a pipe. In TextMate BETA 8, it does select a line.
Well, the mail was not composed within TM as I do all my mail on my home machine with mutt/xemacs thanks to ssh & screen but like I said, as an heavy Ruby user, I'd be very annoyed if opt-shift-l didn't generate a |.