This is business as usual, as far as DirectX is concerned. DX 10.1 hardware will be backwards compatible with DirectX 10, but current DX10 hardware won't be forward compatible. So games looking to support DX 10.1 still need a DX 10 rendering path to support today's DX10 cards. Think of it like when Microsoft released DirectX 9.0c with added Shader Model 3.0 support. Also, don't worry too much about it requiring SP1 (which isn't out yet).
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