Adobe has just released a Lightroom 5.2 beta build, the follow-on from Lightroom 5.0 released a month an a half ago. (There is no “5.1”.)
This build fixes the big Publish-selection bug introduced in Lr5.0. Adobe doesn't suggest using a beta build for real work, but FWIW, I deem the risk from the known 5.0 bug much worse for me than the risk of unknown new bugs in the 5.2 beta, so I'm already using this 5.2 beta for my real-world master catalog.
Unlike most Lightroom dot releases, this one has more than bug fixes and new camera/lens support... it actually has a few new features, including a feather slider for the spot-healing tool. Further details and the download link at Adobe's “Lightroom Journal” blog.