However, before getting too excited, this is not a radically new vertex buffer manager for these two ATI Gallium3D drivers that support the spectrum of Radeon GPUs. R300g is responsible for ATI R300 ASICs up through the ATI Radeon X1000 (R500) GPUs. R600g currently covers the R600 (Radeon HD 2000 series) through the latest Radeon HD 6000 (Northern Islands) and Fusion (Ontario) chipsets.
What these few code commits pertaining to the "new vertex buffer manager" do is unify the "new" vertex buffer manager between the two drivers. This vertex buffer manager was originally written for R300g and later ported to the R600g driver. This resulted in effectively the same manager appearing in two code-bases.
With the latest Git master, the ATI Gallium3D vertex buffer manager is now living independently with its ~900 lines of code living as a Gallium3D utility. There's no longer any code duplication and hopefully any future optimizations will benefit both drivers.
See here, here, and here. The vertex buffer manager work was done by Marek Olšák, a member of the Phoronix Forums.