Does iDVD allow creation of DVD movies burned to CD-R rather than DVD-R? Certainly the movie would have to be significantly shorter than if it were on a DVD-R, but it would allow for small home movies or similar things.
Most DVD players can read VCD's.
Maybe that's an idea.
I think it is possible for iMovie to export a project to Toast, meaning a VCD format. It will create a VCD with the MPEG1 movie on that, readable for most DVD players.
SVCD will be possible (Toast 6, presuming rumors are true), very soon.... this makes MPEG2 (same as DVD) possoble on a CD too.