I dont recall that versionable was enabled by default on older versions. One easy way is to set a content rule on company home to add the aspect to new items (of type content) and make the rule work also on subspaces.
Yeah, i thought it was interesting when i first setup Labs 3.0……Everything in Share auto versioned or made teh user version to whether through share point or the web interface.
everything in my test share has the "versionable" aspect applied…..Im guessing there is an auto version i can apply to the root as well