Export versions of a document (/.DocumentRevisions-V100)
This is not an answer, but it is too much for a comment. Might be somebody can add information here.

You might think the different versions are stored within the file itself. This is not true. The different versions are stored in the following directory

/.DocumentRevisions-V100


You need admin rights to browse around in that folder, so changing its rights using the following command makes it possible to see its contents without admin rights.

sudo chmod -R 115 /.DocumentRevisions-V100


Now you can use Finder to look around in your versions.

open /.DocumentRevisions-V100


You will notice that the directory structure is a bit un-human, and it looks a bit like the iPod structure if you ask me. The different versions of all your files are stored within this folders. Probably, the /.DocumentRevisions-V100/db-V1/db.sqlite-wal file contains the most important information. But unfortunately I can only guess how these versions are stored.

It might be possible to create a smart folder that handles the contents of /.DocumentRevisions-V100 to fetch the versions you want.

(Most of this info is from: http://www.maclife.com/article/howtos/everything_you_need_know_about_versions)

New:
The /.DocumentRevisions-V100/PerUID/[0-9] directory contains the files per user ID (run the id command in the Terminal to know your user ID). This is were the different versions of all your docs are stored. When I copied this Directory to my desktop and changed permissions, I was able to do spotlight searches on them and find all versions from 1 certain file.