While not enabled by default in Mesa 7.5, the Mesa mainline code-base contains all of the necessary Gallium3D work. There are Gallium3D drivers for the Intel 915 and 965 chipsets, the NVIDIA NV04/10/20/30/40/50 series through the Nouveau project, the ATI R300 series, trace, softpipe, a failover, and the Cell hardware. Gallium3D also has in-tree state trackers for DRI2, EGL, g3dvl, GLX, Python, WGL, and X.Org.
Brian Paul of Tungsten Graphics (now owned by VMware) announced today that he intends to release Mesa 7.5 in the coming days. Specifically, he hopes to release Mesa 7.5 this Friday. It hasn't been that long since Mesa 7.3 has been released (let alone Mesa 7.4), but the 7.5 release is imminent. Brian explains, "I'm looking at making the 7.5 release on Friday. The main objective of this development release will be an initial milestone / roll-out of the Gallium bits. Then, I'd like to quickly create the Mesa 7.6 branch for stabilization. git/master will then again be open to any/all development."
Besides rolling in Gallium3D, Mesa 7.5 supports new OpenGL extensions and has various other changes and new features. The announcement of the plans to release Mesa 7.5 on Friday were described on the Mesa3D development list.