I like the feature in git, where commands that produce long output get piped to $PAGER.
This means, that if you do a "git diff" and its output will not fit into the current terminal window without scrolling, it will get piped to "less" by default, so that you can easily search and scroll in the output. Additionally (and that's the main point IMHO) it does not pollute your scrollback history (when you exit from your pager, the terminal will only display the call to the command, but not its output).
Luckily, there's a plugin for bzr, which provides the same functionality: bzr-pager
You can install it as follows:
mkdir -p ~/.bazaar/plugins && \
cd ~/.bazaar/plugins && \
bzr branch lp:bzr-pager pager
You may want to file a bug/wish at https://bugs.launchpad.net/bzr-pager.
Otherwise, you can extract it from the bazaar repo quite easliy.
What do you want it for?
I've updated the code in the post (you can give "bzr branch" the directory to create).