With Google Applications I feel that it makes for a good 'home user' application when managing personal items, lists, or any sort of power application you may want to tool around with, all in all Google APPS is a great(powerful) resource, but imo not for large scale office use...
Open Office is a great route for open-source applications for offices, and Lotus Symphony; man, I have been using that for some time, but I don't know...It seems to demand a decent amount of CPU and Memory resources.
As for Google Apps/Office, if they do go any further with it, I have this hunch they will be selling it, not publishing it as an open source item.