Apple has seeded the third beta of OS X Mavericks 10.9.5 build 13F14 to developers this morning, just six days after the previous beta and all its bug fixes were released.

Mac fans are anticipating the release of OS X Yosemite within the next few months, but Apple is still making refinements to Mavericks before setting it out to pasture.
OS X 10.9.5 build 13F114 can be found in the Mac Dev Center, and while the seed note does not mention any new features that may have been added, there are certainly a number of new bug fixes that have been added.
Apple is still asking developers to focus on Safari, USB, Graphics, USB Smart Cards, and Thunderbolt issues in in Mavericks beta. A new beta for OS X Yosemite was also released last week that included a redesigned calculator, new Safari options, and other tweaks.