Per discussion at last week's Ubuntu Developer Summit in Barcelona, the latest version of byobu (2.8) has dropped the "diversion" of /usr/bin/screen.
In previous versions of byobu (and screen-profiles), /usr/bin/screen was actually a wrapper script that prompted you to choose your profile, and then launched the real /usr/bin/screen.real with byobu's configuration.
This has proven to be controversial with some traditional GNU screen users. Also, while most of screen's parameters can be passed directly through byobu, some of them cannot.
Thus, from byobu-2.8 onward (and in Ubuntu Karmic Koala), users will need to launch using the byobu command, rather than the screen command.
Note that if you really want to run byobu when you type screen, you can add the following to your $HOME/.screenrc file:
- source $HOME/.byobu/profile
Sorry about any inconveniences...