If I had 20 directories under trunk/ with lots of files in each and only needed 3 of those directories, would it be possible to do a Subversion checkout with only those 3 di
Sort of. As Bobby says:
svn co file:///.../trunk/foo file:///.../trunk/bar file:///.../trunk/hum
will get the folders, but you will get separate folders from a subversion perspective. You will have to go separate commits and updates on each subfolder.
I don't believe you can checkout a partial tree and then work with the partial tree as a single entity.