Aside from preparation work on Wine's Direct3D command stream support, there's also an updated Mozilla Gecko web rendering engine back-end, and other changes:
- New version of the Gecko engine based on Firefox 24.
- Preparation work for the Direct3D command stream.
- Window management fixes in the Mac driver.
- Support for IPHLPAPI functions on Android.
- Various bug fixes.
These are details from the official announcement at WineHQ.org. In all there's 48 known bug-fixes for Wine 1.7.3, including many Direct3D-related changes in the past two weeks.
The Direct3D command stream work -- which is still to-be-merged and only some prep work made it into v1.7.3 -- allows for very noticeable Wine Direct3D performance improvements. The WineD3D changes move OpenGL calls into a separate thread and can yield 50~100% performance improvements while also clearing some outstanding bugs.