Published in early September was work on Wine Direct3D performance improvements that could yield 50~100% performance improvements for Direct3D improvements. This work by Stefan Dösinger offloads work onto a separate command stream / worker thread for WineD3D. These Wine Direct3D improvements are really to benefit CPU-limited games right now running in Wine.
Some prep work on the Direct3D command stream support was pushed into Wine 1.7.3 and now additional changes have landed for Wine 1.7.4. Hopefully in the releases ahead we will see the actual WineD3D command stream changes land and begin boosting the performance for many Windows games on Linux.
Other changes for Wine 1.7.4 include support for the Cocoa-style full-screen mode with the Apple Mac driver, Winsock improvements, and various bug-fixes.
More details on the Wine 1.7.4 changes can be found via WineHQ.org.