Apple has seeded a new build of the OS X Yosemite beta to AppleSeed users and developers. The seed notes for build 14C78c say that testers should focus on Wi-Fi connectivity, indicating that Apple has done some work in that area to resolve outstanding issues.
The update comes in at about 470 MB and is available now in the Updates tab of the Mac App Store. It should be available shortly on the OS X Developer Center as well.
FTC: We use income earning auto affiliate links. More.