According to a story on the Inquirer, DirectX 10.1 will make the current crop of DirectX 10 cards more or less obsolete, as the new revision requires new hardware support. This is not going to make the GPU guys happy at all, especially when you consider the time it takes to design a GPU these days.
But what's even worse is the current install base of DX10 cards, as everyone that's spent their hard earned cash on one of these babies, will have to save up more money again for a new graphics card just to get a few new features that will appear in the latest games.
According to the Inq, DX10.1 isn't meant to add much that the game developers are really likely to care too much about, as the new revision makes certain optional DX10 features compulsory. One of those features is 4x Anti Aliasing as standard, but Microsoft hasn't limited to what kind.
With DX10 hardly out of the door, one has to wonder why Microsoft has been so quick to push out a new standard that doesn't add anything sensible, but instead causes a lot of issues. And remember, you need to have Vista SP1 for it to work and with game developers struggling to do DX10, who is even going to bother with DX10.1?
You can read the Inq's story here