Gaim has a useflag (evo) for having it makeing a plugin into evolution. Gnome-panel have one useflag (eds) for making the clock display the calendar. To diffrent things and two diffrent useflags (evo and eds), still I believe it would be better with one (evolution) becouse I believe what both useflags does is only making the packages support evolution. Clearifyed: the useflags "evo" and "eds" should be merged into one useflag with a name speaking for itself like "evolution".
no, evolution data server does not depend on evolution, and evolution data server support in gnome-panel does not require evolution. Having an evolution flag would not make sense and be misleading, which is why there are two flags.