This has never really been an issue for me in the past, but at the moment I find myself working on movie projects at 24 fps and HDTV PAL projects at 25fps in parallel. I keep getting tripped up by sequences defaulting to the wrong frame rate on import (admittedly, when I forget to interpret the footage manually)
It strikes me that this really should be a project setting, rather than an application preference. Or at least there could be a project setting that overrides the application preference.