Good thing is that several different unique ids can be interlinked to the same entity. I was using Wikipedia page_ids and IMDB's titles when playing around with it previously. It's a little bit messy, but it works.
For example (for those that are unfamiliar with the richness of this data), visit: http://www.freebase.com/view/en/y_combinator
And there you'll note that Y Combinator is mapped to the official site, it's Wikipedia page, it can tell you who the founders are, etc. If you link to Paul Grahm, you can then find out what his personal site is, and so on.
I do hope Google will do something cool with this acquisition.