Interestingly Microsoft has recently announced that office 2010 will have an online component. For those with a microsoft password account it will be for free. What it offers which google docs doesn't is integration with the offline Microsoft Office.
One of my annoyances with Google docs is how you cannot start a document while offline. There are times when you may not be online.
There is a sync between google docs and openoffice, called 0002dg, its never really worked for me on a Mac, I suspect because at the time my Mac osx use an older version of Java.
Anyway I think that that with Microsoft announcement there is certainly a bit of competion in the air. For Goolge I think the easy way is to get the sync integration going really well with the whole open office suite.