Right now, the folks at Red Hat are sort of holding the UI design reigns for the OLPC. Marco has told me that they they want to make the work more open, but it will take some time to get there. They are under a tight schedule, and releasing their work to the public takes time and energy, so for the time being I'm mostly just going to try to follow their lead and put as much of my work out in the open.
You can read about my understanding of their design direction here, but this is what they seem to be going for, in short:
Simplicity. Their apps are generally simpler than the stuff we are used to seeing on the Linux desktop. There are no menus, and they are using pretty basic toolbars with no labels. Abiword has a lot of features, so getting down to this level of simplicity is going to be tough.
Collaboration. They are really focused on the online presence stuff offered by (I think) Galago. And other people are excited about it too. Marc and Martin have been doing some amazing work with AbiCollab, which fits in beautifully with the Red Hat folks' vision. To really get this cooking on the OLPC, I think AbiCollab will need to integrate with the OLPC's presence and chat infrastructure.
Direct Editing. Chris Blizzard mentioned this to me, and if I interpreted him correctly, what this means is moving away from the open-edit-save cycles, and towards just editing documents in place. "Instant Apply" for documents, if you will. I think this makes a lot of sense, especially in the context of AbiCollab. When lots of people are editing the same documents, it just seems simpler to have one current version of the document. Having an open and a saved version would just create confusion. Doing this in AbiWord might be as simple as removing the save buttons and having documents be automatically saved on exit.
Details.
Be a literacy aid. I think it's critical that AbiWord be useful not just as a typing tool, but as a learning tool. Literacy is one of the biggest educational problems in the countries OLPC is headed for, and AbiWord could become an excellent tool for learning to read and write.
Be usable by people who can't read. Many OLPC users won't be able to read, and there are at least two things we can do to support them: use for pictoral representations in place of textual ones wherever possible, and make sure AbiWord a safe place to play, by providing good undo and guiding users away from catastrophic actions.
Sources: OLPC Hardware Specification