I sometimes have the need to put the same post on multiple DW and LJ comms. Having the ability to crosspost to communities would be fabulous regardless if you are the admin or not.

Since crossposting is a paid feature, in that you can crosspost more if you have a paid account, I don't know where the balance point is. Also, I see the huge potential that a feature like this could have for generating SPAM. I think that more discussion needs to happen about crossposting to communities.