Some contributors to both the Wine and Mesa/Gallium3D projects are up in arms as there was some initial confusion over whether this Direct3D 10/11 state tracker uses any code derived from Microsoft. This state tracker does not use any Microsoft code, as confirmed by its developer. However, some are still uncertain about the legal status of Direct3D on Linux (along with the *BSDs and elsewhere that Gallium3D is compatible) and whether Microsoft could end up providing legal challenges to its adoption.
Corbin Simpson even wanted to pull this Gallium3D state tracker out of Mesa, but VMware's Jose Fonseca is in opposition to it being dropped and is calling for more discussion (mailing list). In another message, Jose mentions the D3D1x state tracker could be split into run-time and client driver components where the Wine developers (or ReactOS) could then re-code the run-time if they are concerned about the one living in Mesa.
The debate over this fascinating Direct3D 10/11 state tracker is ongoing. Meanwhile, Luca has committed Wine DLLs that use this state tracker so that in fact Wine can now hook into Gallium3D for this Microsoft Direct3D acceleration on the GPU (or on the CPU if using LLVMpipe). See this Git commit.