No it does not.
Definately a feature to look out for in GarageBand 13. I'm also waiting for that that feature in Logic.
However I don't know how they deal with the asset files. Also, it seems that Apple hasn't thought that through with all the side effects of versioning. As long as your file (pages, numbers, etc) is only a couple of MB big then it is not a problem. However, when you work on a file that is closer to 500MB then you see your available disk space disappear in no time.
I had 20GB left on my MacBook and and in a few days I was running out of disk space when working on an iBooks Author file. Until I found out the problem with versioning.
So be careful what you wish for
Hope that helps