Hey, I'm really sorry for the delay in my response! I've been sleeping all day and working all night (literally!) and just have barely been keeping up with anything, including the GoF.
Anywho, we do have plans for how we want to produce foliage for the game. I have already purchased a nice bit of software which will create trees and I'm looking into a program that will produce smaller natural objects as well (rocks, plants, mushrooms, grass, etc).
Because of this, I don't see a need for us to manually model very much in the way of foliage at this point. I'm positive there will be many cases where the 3d objects I can create with these programs won't be exactly what we need for a specific task in the game though, and that sounds like an idea time to come knocking at your door, if I may!
As for 3d stuff to make right now, nothing is coming to mind, to be honest. I'm having a lot of techincal problems with trees at the moment (well, one technical problem that I have no idea how to fix!

) and until I get past it, I'm not exactly sure what we'll be needing in the near future.