Ive been looking for a product similar to google apps but theres nothing out there thats "free" that allows me to do this for our work environment. Budgets are tight, yo!
I also took a look at Alfresco for a sharepoint alternative but that doesnt integrate incredibly well with office so that you can check out items. It does document control pretty well though.
My main reasoning for google apps was because it allows collaborative editing. If this adds it like the summary says it will, I would test it out immediately.