According to the Official Google Blog:
Second, today we demonstrated new mobile editing capabilities for Google Docs on the Android platform and the iPad. In the next few weeks, co-workers around the world will soon be able to co-edit files simultaneously from an even wider array of devices.
This is good news for iPad owners who will no longer need to buy an app to edit Google Docs. (Not to mention making a number of iPad-owning SLAW contributors very happy.)