We don't have any specific idea what the new things inside the new Direct X 10.1 specs may be and we are well aware that the Vole can simply change its name to Direct X 10.a or something of a similar sort. That happened recently with Direct X 9.c which was supposed to be released as Direct X 9.1, but that was more of an Nvidia versus ATI specification fight.
It's funny though, as Direct X 10 looks quite ready and you can already play about with the Direct X 10 SDK beta. As Vista got postponed a few times, the DirectX chaps figured out a few things that they can change and fix. The Windows Graphic Foundation 2.0, or what we now know as Direct X 10, has been finalised for more than a few months now and there are no changes to those specs. It is a done deal.
That is why there will be a new one, but we don't yet know what new stuff it will bring. ยต