Mesa 7.8.0 was released in late March but then just days later Mesa 7.8.1 came to fix a major problem. However, this made Mesa 7.8.1 not the usual Mesa x.y.1 release that offers stable and back-ported fixes from what in this case is the Mesa 7.9-devel code.
Mesa 7.8.2 offers up stable fixes and other general improvements to the Mesa graphics stack, but it doesn't bring forth any notable changes. Those interested in Mesa 7.8.2 can find its release announcement on the mesa-announce list.
Meanwhile, Mesa 7.9 is looking to offer up better ATI Gallium3D performance, LLVMpipe optimizations, Gallium3D Stream-Out support, the initial ATI R600/700 Gallium3D driver, and potentially the ATI Evergreen Mesa driver for ATI Radeon HD 5000 series hardware. There's also a variety of bug-fixes and improvements to Mesa's core OpenGL support along with the various hardware drivers from Intel to the NVIDIA-targeting Nouveau driver. Mesa 7.9 should be released in the coming months.